One thing I'd add is that the biggest challenge isn't collecting more biometric data—it's deciding when not to act on it.

Wearables generate continuous signals, but those signals are noisy and context-dependent. A poor night's sleep, illness, travel, or even a loose sensor can change the data dramatically. AI systems need confidence thresholds and the ability to say "I'm not sure" instead of forcing a recommendation.

The most valuable fitness AI won't be the one that gives the most advice. It'll be the one that knows when the available data isn't reliable enough to make one.