Why does Finny train gene for the 1944 olympics?

Finny always planned on participating in the Olympics, but that dream ended after the accident. Thus, he decided that he would train Gene to participate for him.... the next best thing.

"Did I ever tell you...that I used to be aiming for the Olympics?...Well, I was. And now I'm not sure, not a hundred per cent sure I'll be completely, you know, in shape by 1944. So I'm going to coach you for them instead."