Some people, myself included (for reasons similar to yours), believe that Tai Chi is just a much slower version, or pace, of Kung Fu (for the most part) for balance. There are many other benefits, such as improving and maintaining balance and flexibility.
I have spinal stenosis (cervical), degenerated disks and a couple of fusions. On top of that, I have Osteoarthritis and Fibromyalgia; I've had nearly all of these for almost 21 years and I'm not even 48 years old. If I were to skip my morning Tai Chi + stretch routine for any reason, which gets oxygen to more muscle tissues and promotes regrowth of nerve and brain cells, then I would be in too much pain to eat, sleep, smile, socialize or laugh. This makes me hurt even more.
Yoda said; "There is no 'try.' Only DO, or DO NOT!" Yoda only said DO. He never said to hurry up. I am already on disability. I am not going to let that own me.
I have some disabilities; they don't have me. I am not "DIS-ABLED"! I am Michael. I am not as fast, strong, or agile as I was at one time. I can WALK and TALK! I can still LAUGH, LOVE, ENCOURAGE, LEARN FOR FREE, AND SO MUCH More!
I could also be angry, hateful, spiteful, and blame others for reasons that not even my doctors have figured out. I could waste my time with negative, hurtful, useless feelings. I could. But I don't want to and I REFUSE TO!
Martial arts is more than just physical movements to be memorized. In fact, the mental and spiritual, the Chi (Qi), that is the hard part. You want to see what is after 1st and 2nd grade? A ton of "Internal" that is not easily taught and is even harder to learn. You, I, we. We are more. So? Do, Be, Become MORE.