I approach the dilemma a different way. If I don't feel like building, I look for inspiration all over the place, between the forums and the reading materials available . . . anything model related usually helps a great deal.
Unlike Harry's approach, I try to keep a routine almost every day because I have found over the long run that building models DOES HELP steady my nerves, my mind. Now that I am middle aged, I am trying to keep hand-eye coordination sharp . . .
I do try to build as often, but I also do take long breaks, and those are really important too.
I think this is an extremely serious and useful topic of conversation . . . .