First off, look at some of your older code. How recently can you go back and look at some of your older stuff and thing, "Wow! I wouldn't write it like that now!"?

If it's not more than a year or two ago, then you're a constantly improving developer and I wouldn't be too concerned. However if you're still writing things exactly the same way 5 years later, you're either not learning, or you've got some awesome niche where you're almost the only VBA developer in your town and you're charging out at $1000+/day. ;-)

For me, probably 90% of the time, I love programming for the fact that there's always cool stuff to learn. But the other 10% of the time, I hate programming because you've always got to learn new stuff. (only half-joking... so it's realistically 5%)

It's an awesome field to be part of. You don't necessarily need to compare yourself to the gurus. I'll never ever be a Carmack/Torvolds/Knuth... But in my field, I'm pretty decent and am appreciated by my clients.

And the day I stop learning is the day I'm dead.