I'm very much of the belief that you should know what you are good at and not be afraid to say.  The other side of this is that you should also know what you are not good at.  And, what's more, be prepared to do it.  The immediate benefits may be small and the experience rather less enjoyable than the easy run of something you can do, but this stretching can bring other positives.  Number one, learning is always good - I don't think it really matters what, just the act of stretching the brain.  Number two, you can gain a new skill.  And number three, it keeps you humble, as I found when I went to a Spanish conversation class...

She knew what she wanted to say, but finding words was impossible.  The man paused, then turned away; her Spanish had left her drinkless once again.