This was more of an introspection, but i used to be rather depressed. When I started reflecting on life and all I could contribute or succeed at (this was actually years ago, not specifically this question). I realized that if someone 1000x more intellect / capable / knowledgeable came along, everything I could add or solved from an intellectual perspective would be useless.

After meditating / contemplating this for quite some time, we are talking the order of months. I realized that even if someone knows 1000x more, they still may not know your niche. More than that, everyone has niche expertise from their lives, which no one else can access (from their experiences).

I don't know how I got to that conclusion, or how to explain it. It was the hardest problem I solved, because it's something that had to do with a change in perspective and personality. It also is what helps me listen to others in debates and to be much more open minded. I wouldn't say it's that big of a deal, as I felt it was part of growing as a person, however many around me don't seem to recognize that. When I hear "they are naturally gifted" or "I'm not smart enough", I feel those are people who haven't had the same realization (i.e. experience).

Anyway, that was probably the most difficult and profound problem I solved for myself. What motivates me.