Absolutely! I'm 38 now. I use to play pro baseball. I've always been a good athlete so this really does tame your ego. I love tennis myself but I know better. I run on very little cortisol stores so I know if I do anything slightly strenous (for 20 minutes max) one day I can't do it the next. My body can't recover the cortisol fast enough and my body reverts to using adrenaline. Actually for the past 3 years I've been running on adrenaline at least half the time. There will be night where I might get 2 hours of sleep cause the adrenaline has me wide awake. I can then go into work without being exhausted. But I know eventually my adrenals will crash if I go another day or two like that. Actually, as I write this my body is pumping on adrenaline. I can tell by my heart beat/rate. It changes and feels different.