Don't think it has much to do with gay or straight. People who take care of themselves over the age of 40 are probably people who established the habit when they were younger.
I don't mean to hijack your thread but this is a subject that gets under my collar; people who talk about changing their health habits and working out, and then give up. From what I've seen, it comes from these reasons, mainly:
-- people look at exercise as if it were one more item on a list of chores to be checked off when, to be successful, you have to look at it like eating, pooping, bathing, brushing your teeth, etc. It's just part of your daily life. You do those other things without much deliberation and you approach your workouts and/or exercise the same way.
-- people have unrealistic expectations or an unrealistic timeline. It depends on many variables (age, prior conditioning, present health, etc.) but, from my experience, I'd say it takes about four months for real, lasting changes to begin. You can reap benefits almost immediately, but things like improved balance and coordination, muscle memory, a stronger mind/body connection...things that will serve you in every part of your life...these take time, and most people get bored or discouraged and give up before they experience them.
-- sorry, but most people are LAZY; they never learn one of the most important lessons that fitness can teach: you can't always trust your inclinations. You shut the alarm off in the morning and you do not feel like getting out of bed. You count how many times you got up to pee in the night, the crazy dream that woke you up; you just know you need more sleep because you feel so tired. But you know what? If you get your ass out of bed, nine times out of ten that feeling goes away! Yep, believe it or not. So, here's another lesson working out can teach: discipline is not a trait you're born with, it's a skill you develop through practice, just like any other.
My two cents. Most of us are creatures of habit. The main thing holding back people over 40 from getting in shape is all the time wasted developing bad habits that they will need to change. All you young guys out there: start now. It will be much easier when you get to be my age.