a), b), and c) are all true for any craft. Ars longa, vita brevis. Writers, musicians, and athletes all feel that and that's ok. That's part of being alive.

It's just you're getting older and it's time for you to find better balance in your life. Relax, you will not fall behind since we're all getting older. It's an even field.

And it's even worse with athletes. In engineering you're supposed to hit your prime at about 35-40. That's when an average footballer career is over. We're kind of privileged in that regard.