What do a 13-year-old aspiring veterinarian, a 75-year-old body builder, and a citizen volunteer in Ukraine have in common? They've all decided to go big.

Small, careful steps are all well and good. But where is the challenge in that?

On this Now or Never, people are stepping outside their comfort zones and pushing the boundaries of what they think is possible. It's time to go big — and hope, in the end, it all works out.