Saltar al contenido

Who's behind it

David Rentería.

Personal trainer and 1:1 habits coach. The capabilities of an elite athlete — physical, cognitive and recovery — without being an athlete and without the effort that level demands.

Today I do the same with people who'll never step on a mat. Leaders, business owners, founders, executives, workaholics — people who hold up a team, a company or a family, and who stopped holding up themselves years ago. I translate what makes a competitor perform for a life that doesn't revolve around training.

Aspire Leaders Program
Aspire Institute, born from a Harvard-founded initiative
Colombia national team
Judo
Valle regional team
Wrestling
Departmental champion
Judo
Departmental champion
Jiu-jitsu
15 years
competing
5 years
training others
+200
people coached
6
clients at a time, max
100%
virtual · LatAm & Spain
0
guarantees claimed to date

Where I come from

  1. 01

    The mat doesn't negotiate

    At the club they saw before I did that something was there. Judo and wrestling, Colombia national team, Valle regional team, departmental champion in judo and jiu-jitsu. But in a combat sport nobody gives you a point for what you promise: you step on the mat and in five minutes it's clear whether the work was done. That teaches something you don't learn from reading — that Saturday's result was decided on Tuesday.

  2. 02

    The body breaks, and gets rebuilt

    Fifteen years of competing are also injuries, weight to cut in a week, bad seasons and coming back. You learn to read your own body because you have no choice: when to push, when to stop, which signal is fatigue and which is the start of an injury. That reading is exactly what an executive doesn't have, and what they need most.

  3. 03

    And then, teaching it

    First self-defense. Then five years training people who aren't athletes and don't want to be: people who run a company, a team or a practice, and who arrive exhausted. More than 200 people. The work wasn't teaching them to train: it was translating what makes a competitor perform for a life that doesn't revolve around training.

Talent gives you the first edge and it runs out fast. The second — the one that wins championships, and the one that changes a body at forty — is built by doing the boring things well for years, with someone beside you who tells you the truth when you don't want to hear it. That's what I bring.

The credential

Where the method comes from, and who signs it.

Aspire Leaders Program 2025 from the Aspire Institute, the organization born from an initiative founded at Harvard University. One of 5.463 who completed it, of 26.441 admitted across 180 countries.

The Aspire Institute issues it, not Harvard

The Aspire Institute's leadership module is designed and delivered by Harvard faculty, and its career resources are co-created with Harvard Business School; the program is signed by two of its professors, Tarun Khanna and Karim Lakhani. The credential is the Aspire Institute's, not Harvard's — specific, verifiable, and that precision is the point.

The mechanism

What makes an elite athlete perform isn't training more. It's everything else.

An elite athlete doesn't perform because they train more hours: they perform because everything around the training is measured and adjusted — how much they sleep, when they eat, how they recover, what changes when a week goes wrong. That infrastructure is what almost no one has outside professional sport, and it's what fits into two hours a week. The training is the easy part.

Physical

Body composition, strength and work capacity. What you can see, and the only thing a normal program looks at.

Cognitive

Sustained focus, clarity and the 4 p.m. drop. It's what an executive notices before the scale.

Psychological

Stress tolerance, impulse control and the feeling of having your body back. It's what decides whether the change lasts.

Health

Sleep, metabolic markers and recovery. It's the base the other three stand on, and the one nobody measures.

Before you hire anyone

How to choose an online personal trainer without getting it wrong.

Six criteria, with the exact question that checks each one. They're written to use with anyone — me included. If someone can't answer one of them, you already know what that means.

  1. 01

    That they work from your data, not a template

    Ask to see what they ask you before they hand you the plan. If the plan arrives with no bloodwork, no real schedule and no injury history, it's a template with your name on top.

  2. 02

    That the adjustment is weekly, not monthly

    Ask how often it's reviewed and what happens when a week goes wrong. A plan reviewed monthly is a plan that ignores three weeks of data.

  3. 03

    That you talk to whoever signs the program

    Ask who answers the messages. If the answer is 'the team' or 'app support', you're paying for 1:1 and getting product support.

  4. 04

    That they have a client ceiling and say it

    Ask how many people they coach at a time. Whoever has no number has no ceiling; and with no ceiling, your follow-up is what gets dropped when the next one signs.

  5. 05

    That the guarantee has written conditions

    Ask for the document. A guarantee with no published requirements isn't a guarantee: it's a sales line interpreted when it's time to pay it.

  6. 06

    That they can tell you no

    If nobody has told you yet who the program is NOT for, they haven't described the program yet: they've described an ad.

A seventh, and this one no question checks: that you actually like the person. You'll talk to them every week for three months about things you don't usually share. If after the first call you don't want a second, the best protocol in the world won't fix it.

Is it worth paying for a personal trainer?

The honest answer starts with the case where it isn't: if you've never really tried, if you have plenty of time to try and get it wrong, and if you sleep well — don't pay for it. There's enough free information and it'll serve you.

Where the math changes is once you've already tried. Three failed attempts aren't three lost months: they're three months of data nobody read. And there's a physiological reason trying it alone fails more than it seems — sleep debt anesthetizes the perception of the debt itself: a week of short nights leaves you making decisions with impairment comparable to being over the legal driving limit, and you don't feel it.

Translated to your week: your baseline for "I'm fine" has already shifted. That's why the program starts by measuring, not training.

What it costs: an initial assessment of $20 USD (credited in full if you join), and $300 USD/mo with a 3-month minimum. If in 3 months, doing the minimum, you don't reach 2–8 kg or the goal we agree, you choose: I refund you or I keep working with you free until you get there. All the detail is here.

Who it's worked with

Real client results, with their permission. Not promises of what will happen to you: what happened when someone kept the protocol's minimum.

  • Luisa

    −7 kg · abdominal area

  • Geraldin

    −4.2 kg

  • Isabel Flores

    −11 kg · 40 min/session

  • María Ramona

    Visible recomposition

Photos and full stories on the Spanish site.

What people ask before they write to me

Who is David Rentería?

A personal trainer and 1:1 habits coach who adapts elite-sport protocols — sleep, load, recovery and measurement — for executives and professionals with a real schedule. He works fully virtually with clients across Latin America and Spain, with a real capacity of 6 people at a time.

Is it worth paying for a personal trainer?

It depends what not doing it is costing you. If you've trained for years with no measurable result, if you sleep badly chronically, or you've already tried three times on your own, what you're paying for is no longer the trainer: it's the time you've spent repeating the same thing. If you've never really tried and have plenty of time to experiment, start free: there's enough information online.

How do I choose an online personal trainer?

Six checkable criteria: that they work from your data and not a template, that they adjust weekly, that you talk to whoever signs the program, that they have a declared client ceiling, that the guarantee has written conditions, and that they can tell you who it's not for. The first three you verify before paying, with questions.

How much does David Rentería charge?

Initial assessment $20 USD, credited in full to your first month if you join. 1:1 program $300 USD/mo with a 3-month minimum, or $900 USD paying the quarter upfront. No hidden costs: the full breakdown is on the offer page.

What training does he have, exactly?

Aspire Leaders Program 2025 from the Aspire Institute, born from an initiative founded at Harvard University; its leadership module is delivered by Harvard faculty and signed by two Harvard Business School professors — the certificate is the Aspire Institute's, not Harvard's. Plus 15 years of his own competitive sport, which is where the method comes from. He isn't a doctor: any clinical finding is coordinated with your treating physician.

Who is this program NOT for?

For anyone after a one-week plan, anyone unwilling to log metrics, and anyone who wants results without changing anything in their schedule. Also for anyone who needs medical treatment: that's for a doctor, not a trainer.

Which countries can he work with?

Any country in Latin America or Spain. The coaching is 100% virtual: a video call adjustable to your schedule and direct daily follow-up, without depending on a city or a specific gym.

Initial assessment

Loading the calendar…

30 minutes · by video call