Kai had been answering the same cutting questions in DMs for a year. Instead of building another PDF, he ran a 12-week paid challenge with 94 participants staking $30/week. He finished with $11,200 in his account and a 22% upsell rate into 1:1 coaching.
The setup
Kai Martinez (@cutwithkai on Instagram, 68,000 followers, roughly 6% engagement) had been coaching bodybuilding cuts 1:1 for three years and kept hitting the same wall: every follower who DMed him wanted a plan, but most couldn't afford his $900/month coaching retainer.
He considered a PDF course. Two problems: the 40% platform fee on Gumroad, and the fact that 65% of course buyers never open the first module.
In February 2026 he ran his first paid OutGrind challenge instead.
The offer
A 12-week cutting challenge. $30/week stake. Four gym-verified sessions per week to stay eligible for the weekly pot. Whoever completed all 12 weeks split the forfeited stakes of people who dropped off.
He announced it with one Reel ("I'm running a 12-week cut with my community — here's how to join") and three follow-up Stories. That was the entire launch.
The numbers
- **94 participants** enrolled in week 1 (1.4% of his audience)
- **Total pot**: $33,840
- **Completion rate**: 71% (vs 12% industry average for free challenges)
- **Stripe fees**: $1,150
- **Platform fee (30%)**: $9,807
- **Kai's take-home**: $11,230
- **Follow-on 1:1 coaching conversions**: 21 participants (22.3%)
- **Follow-on coaching retainer value**: $18,900/month
Why it worked
Three reasons Kai repeated in his post-mortem:
1. **Skin in the game filtered the audience**. The 94 who paid were the 1.4% that would have been his best coaching clients anyway. Free challenges attract tire-kickers; paid challenges self-select.
2. **The infrastructure removed every excuse**. GPS check-ins meant no "my Wi-Fi was out" excuses. Weekly settlement emails from Stripe kept trust high.
3. **The 22% upsell into coaching** was unexpected. Participants who finished the challenge had already demonstrated consistency — they were the best coaching leads he'd ever had.
What he'd do differently
- **Charge more.** Kai ran week-1 at $30/week; his second challenge (May 2026) went to $50/week with barely any drop in conversion rate. The bottom 20% of participants by intent filtered out.
- **Announce earlier.** He opened enrollment 5 days before week 1. His second challenge had a 14-day enrollment window and closed with 138 participants.
Kai is on his third challenge as of this writing.
Published 2/18/2026 · See all case studies