I'm 65 going on 66 and still racing a micro 600. Still own two UAS karts and hope to race them again. Perhaps kart racing will have a revival around here.
Racing is a state of mind that keeps you competitive in all walks of life, personal and business. You won't succeed if you are a lazy lard, you won't succeed if you if question your own abilities and you won't succeed if you are afraid of failure. You make a decision, you go forward with that decision and measure yourself against that decision. Racing is a great mental stimulant, it forces you to own your decisions.
DK