At least in theory, staying healthy is actually quite simple. I think the biggest challenge I've had for years in this area has been thinking that being healthy was a place where I would arrive one day and settle there forever in glory!
#5 I keep track of where I am, where I'm coming from and where I want to be
Please, do not interpret this one, as obsessing with weighing myself and exercising. Because I'm NOT doing that and I do NOT advise you to do it either. That said, I do believe it's important to have an objective measure of where I stand, what I have accomplished and what my future goals are, to keep me motivated.
There are 2 very cool iPhone apps that I find very nice and helpful for this: