Well, as to not offend Benoit, I have to admit that as many years as I've been playing, I don't think I'm as great as I can be (noticed I didn't say suck??), even though time and time again people tell me I'm really good. I live by two rules:
1. Practice! You can never practice enough. I usually try new stuff, nice and slow to get it right, then speed it up until I'm proficient with it. Once I'm proficient with it, then I like to change it up a bit and put my own touch to it until it's too my liking.
My second rule: When you start thinking you've learned everything it's time to stop playing. You'll find out that no matter how much knowledge you tuck under your belt, someone else knows something you don't. Randy Rhoads, who in my opinion is one of the greatest, used to take lessons on the road with Ozzy up until the day he died. EVH, who is a very influential player starting comparing himself to Mozart about ten years ago. I personally think that right after he did that, all his **** started sounding the same. If you think you've reached a peak playing metal....try learning the blues or classical (trust me..it sounds boring but you won't believe the things you can do). The guitar is not only a versatile instrument, it's a freaking blast to play! Play around with it and see what you can make it do, you'll be surprised.
Music washes away from the soul the dust of everyday life.