How do you keep yourself hungry? I've hit a point where life is very comfortable and I don't need to worry about the immediate finances or food or shelter. I've become lazy. I'm certainly not as motivated/hungry as when I was fresh out of uni and broke.
Max's advice here is good even if you don't subscribe to the "I need to be worried about the rent to do decent work" philosophy. I have never met someone who said "You know, I saved too much for retirement", and given that most of us are 35+ years from it a dollar invested today is likely to be a dollar or more of income per life plus $25 to your children or favorite cause after you die.
(Well, less whatever tax your local jurisdiction charges rich plutocrats like yourself.)
