Always try the problem that matters most to you.

But the best problem I ever found, I found in my local public library.

Mathematics... is a bit like discovering oil. ... But mathematics has one great advantage over oil, in that no one has yet ... found a way that you can keep using the same oil forever.

It's fine to work on any problem, so long as it generates interesting mathematics along the way - even if you don't solve it at the end of the day.

I really believed that I was on the right track, but that did not mean that I would necessarily reach my goal

The definition of a good mathematical problem is the mathematics it generates rather than the problem itself.

I loved doing problems in school.