"Life is like riding a bicycle ... to keep your balance, you have to keep moving." ~ Albert Einstein
I have had many loves in my life. Photography, audio, surfing, skiing, backpacking, fishing, and cycling chief among them. None has bit me as hard or as long as cycling. That's because it satisfies me on so many different levels and for different reasons.
I really think the secret to youth is having the "just one thing." I dunno what that means to everybody else, but to me, the "just one thing" is something you are passionate about (my family would say "obsessed" lol).
I hope your friend keeps moving and ultimately finds his.