So I'm 41 and girls think I'm attractive and look young. I'm very fit and very muscular (ex-runner who works out more... more cut than Ryan Hall but not as bulky). I am still learning about all of this myself but here are my thoughts after all these years. For years, I thought my wife simply had a low sex drive but here is what I've come up with the big 3 that I think can improve your sex life:
1. Women are more complicated. It's like starting a fire naturally. Conditions need to be met, managed, and secured. Routine maintenance needs to be made and kept up with for extended time periods. Basically meeting/exceeding expectations with house and kids at a minimal. Extra points for any time you can make her feel like you are looking out for her and taking care of her. Make the bed. Buy her small things. Listening. Invite her on dates. Cook/cleaning etc. Guys will immediately think "oh, I did those things and still nothing." It's not like that. This is just expected and it's not just once. It's a long term commitment. You will never see get sex for any one of these things. This is just the fabric that helps set the conditions imo.
2. Similar to above, a long-term commitment to doing better about listening, hugging, and touching her back.. smiling when she comes in the door. This is big. Think about if every time you or her come in the door, you share something wrong. Think about when you come home and a dog is happy to see you, wagging it's tail and smiling. You need to try to be that dog. Don't tell her about a bill that didn't get paid right when she walks in the door. Just take care of it. Wag your tail. Do the things she wants to do and that make her happy. I'm not a church guy. For me, the only benefit of Church is sort of some quiet time. Guess what, we are now going to Church. Do the things that make her happy.
3. Hardest to hear for us guys but you need to please her. Many females are more complicated with sex as well. If you got a girl that gets off easy, consider yourself lucky. To use a running analogy, for many of them it's a marathon. There's no, let's just get a few miles in. I personally believe that leads to disappointment and they simply won't want to do it very much if at all. So figure out how to please her all the way on a consistent basis and be prepared to do this or some other way, every time you engage in activity.
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One other thing. My wife never initiates. If you think you do these things and it will just start working.. prob not. You still need to initiate. My wife just doesn't feel comfortable initiating. Maybe insecurity about her body, maybe busy, maybe she thinks it's the guy's role. I don't know. Prob some mix of all of the above. I can't really change that. I just continue to have to initiate.
A single unmarried guy doesn't have to do any of this. They may read this and say all of this is crazy. They can just go hook up. Also, a guy with a unicorn girl (i've dated some) may not need to do as much of this either. Some girls simply have a higher sex drive, get off easy, and are less complicated. But I believe the vast majority of women require a lot of the above.