As a very basic MVP, I imagine an Apple Watch app which displays an ‘estimated lifespan’ based on how you’ve lived today.
In other words, if you exercised/ate/slept like this everyday — you would live to XX.
Sat in a whole matrix of wearables, this estimate could actually have some pretty robust inputs:
1) Exercise (steps, HR)
5) Blood glucose
I think this would short-circuit the whole bad behaviour leads to consequences decades later disconnect.