It always amazes me that Colin Baker has remained so loyal to DW. I wonder if there was ever a time (late 80s / early 90s), when he ever thought he'd just give it up totally. The amount of hatred that was directed towards him, the personal criticisms he received, even jokes about the death of his baby in a fanzine at the time, were horrible. An element of that continues to this day (appearing on this forum sometimes), and it's very unjust. Being named "Worst Doctor" year on year must be very gruelling.
Of course, a lot of that has changed now. New fans are coming in and discovering the old stuff, free of all the baggage that went with it. Big Finish has given Colin a new lease of life. The sad thing is that he had to endure so much, just to get to where he is now.
It's a similar thing with Sylvester McCoy. His interview in the last DWM underlines all of that. I'll long remember Tom Baker appearing on Have I Got News For You?, making a joke about the Doctor changing and saying "if you're unlucky, you get Sylvester McCoy".
A role as promient as DW means you're everyone's target and can never switch off. But, then, I read that Sylvester was at some even or other, and a little kid was terrified of a Dalek. Sylvester became the Doctor and rushed to the kid's aid. Even though that kid had probably never seen the Seventh Doctor, poor old Sylvester knows when his job is called for.
Pat Troughton had it right: keep your head down low and stay quick on your feet ...