go for it
Your not even close to being too old... I have weight lifted my whole life and I am very sure it has balanced me. I have a few years on you, but I feel great and keep a positve attitude about things because of my "escapes". Also I know it helped when I had a accident at work early in my life.
Boxing is good clean fun..
Stay strong and "go get um tiger" :) Who knows.. we may see you on TV ?