I do take into account my age  and physical ability, and to tell you the truth it's scary. My body is so broke up from my wild younger years that there isn't much I can do. But I do think about it a lot and try to work out some.
After much consideration, I started to carry in front where my hands are always close to the weapon and I don't have to reach back to access it.
Awareness is of utmost importance in my situation. Believe me, when you get to where I am you think of these things. At least I do.