It's funny I am approaching 40, and my eyesight has been going for quite some time, so some would say I am ahead of the game! (Not to downplay what you are feeling though). Also, I have noticed little aches and pains popping up, which I know CAN'T be good.

To be honest, I think people who say '40 is the new 30' have like a team of specialists, (cosmetologists, make-up crew, personal trainer), like at their disposal. A lot of us don't have that luxury. But, I think I could use more physical exercise though, that might help things a little.