RelentlessAbout Relentless
Relentless is a mental training app for competitive athletes. We connect athletes with mental performance coaches, who turn what they teach into short daily lessons anyone can use.
What we do
Relentless: Mental Toughness is an iPhone app that teaches athletes the mental side of performance. Coaches build programs made of short lessons, and each lesson pairs the coach's voiceover with an exercise and a reflection. Athletes follow a workout of the day, use the exercise library when they need it, keep a journal around competitions, and track their mindfulness, acceptance and commitment as they train.
For coaches, Relentless is a way to help more athletes than they could one-on-one. Every coach has a profile in the app that links to their own site or booking page.
- What it is
- Mental training app for athletes
- Platform
- iPhone, iOS 15.1 or later
- Lesson length
- Usually 2 to 5 minutes
- Price
- $7.99 a month or $59.99 a year
- Free trial
- 3 days monthly, 7 days annual
- App Store rating
- 4.7 out of 5
- Made by
- Relentless App LLC
- Launched
- May 11, 2026
Why Relentless exists
Relentless started with our co-founder Trenton Sandler's own racing. During his first two seasons of college running, Trenton felt he had lost his competitive drive in races. He worked with a sports psychologist and kept researching on his own, and he eventually found an e-book with eight concrete exercises for race nerves. What he liked was that they were exercises, not advice. You could practice them like any other part of training.
That became the idea behind Relentless. Trenton built the first version and brought in Rahul Kumar to develop the app, and the two of them run it today. Relentless: Mental Toughness launched on the App Store on May 11, 2026. Since then it has grown into a platform where mental performance coaches build the programs athletes follow.
Trenton tells the full story on his own site: Why I Built Relentless.
The team
Trenton Sandler
Co-founder
NCAA Division I middle-distance runner at the University of Arkansas and a running and entertainment creator on YouTube, Instagram and TikTok. trentonsandler.com
In the press
- The Extra MileTrenton Sandler's Relentless Pursuit, on founding Relentless (August 2026)
- The RunnerBois PodcastTrenton on what it takes to run Division I, including Relentless
Contact
Email [email protected]. For help with your subscription or account, see Support.
Relentless App LLC
16100 Foster Street
Overland Park, KS 66085