Sometimes I feel incredibly lost and sad... What the hell am I looking for?

... I'm missing something and I don't know what.. I'm 26, live alone, but have many, many friends. Some say I'm quite intelligent, but I don't stay focused on one thing for too long. I just work and snowboard, surf, ride dirtbikes, mountain climb, sky dive, and I feel like I'm still looking for something I have not yet seen. I don't want to miss it before I die alone in a motorcycle accident. I just feel lost.