"There is no "expiration date" to your sex life. Yes, your sex life can and will change as you age. And yes, your physical capabilities will alter. But with every decade you will get wiser about your wants, and you can grow in your ability to understand and communicate what you want, what you need, and why to your partner. Yes, you can keep it sexy at every age of your life!
I can't stress enough, the need to keep an open dialogue around needs and wants as well as "likes." My general motto is if you can't talk about sex, well, first, sex will hit a road block at some point, but more importantly, if you can't talk about sex maybe you shouldn't be having sex? Sexual maturity is an important part of a healthy sex life and person-hood-- and no I do not mean you can't have playful, fun sex. Sexual maturity is about knowing yourself. It's about knowing your body. It's about the desire to want to know your partner's body and what they like. It's about being able to speak clearly as well as receive clearly (the communication from your partner).
My solid belief system on life in general is growth. A close second is exploration...And of course there are other pillars such as stress management, good healthy food, and connecting to people who support you, for example. Keep these concepts close to you- think about them. Really think about how you inject them into your life, how they support or dismantle your sex life. Make a list. Hang out there for a minute. Get organized and be honest. After you make the list, review it and see where there needs to be change- after all, change is good- it's growth.
Small steps everyday.