I loved doing problems in school.

Some mathematics problems look simple, and you try them for a year or so, and then you try them for a hundred years, and it turns out that they're extremely hard to solve. There's no reason why these problems shouldn't be easy, and yet they turn out to be extremely intricate. Fermat's Last Theorem is the most beautiful example of this.

That particular odyssey is now over. My mind is now at rest.

There are proofs that date back to the Greeks that are still valid today.

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.

The only way I could relax was when I was with my children.

However impenetrable it seems, if you don't try it, then you can never do it.