I like to play new things. Usually that's original stuff that either I've written, or someone asks me to write a part for. I regularly come up with ideas that I can't actually play, and so have to practise them. Even if it only takes 5 minutes practise to be able to play the idea, it's still progress, and I'm still a better player. If you don't have similar experiences then I guess you're just always playing stuff that's easily within your abilities. There's nothing wrong with that at all! As long as your enjoying yourself!
What worries me is that I've met several players who consider themselves "average and happy" IE not willing to push themselves or practise, and yet they are trying to play beyond their abilities. There are absolutely loads of bands with bassists and/or drummers who can't actually play the material they're trying to play (to a good standard) and are not aware that they're below par. It really winds me up! Obviously you get these buys on other instruments too, but they can kind of get away with it