Yep, all of the above is good advice 'though I'm not so sure about the "never work outside your comfort zone" bit. Never? Really?
What about giving yourself a challenge every now and then? Ok, don't go messing with critical life support stuff if you don't know what you are doing but other than that what's wrong with applying a bit of "first principles" engineering smarts and having a crack at it?
Keeps me entertained
