"I'm 63 years old and considering starting . . ."
Lots of great advice in this thread. The chief one is starting with the doctor just to make sure. MA is not much of a spectator sport and you will be stressing your heart a bit in the process. The question about age is one that hints at the idea you're aiming at becoming the next Bruce Lee. At 63, it's probably not gonna happen. But, at 63, you can get yourself in great shape in the next few years. I started at 64 and made black belt at 67. You feel like an idiot going thru the paces with kids and teens during the white belt phase, but you gotta keep going. My dojang also teaches BJJ and I avoided it because my health (breathing) couldn't handle it. However, now that I'm a black belt, it's like starting all over again because the training is much more intense and (surprise, surprise) we are being taught BJJ stuff! Can't avoid it! My doctor says I gotta keep it up because it's keeping me healthy. B/P is like a young person, Diabetes 2 under control, weight under control. Enjoy yourself!