Beyond a certain point, fitness doesn't matter. It really doesn't. If you hit the threshold that allows you to be comfortable, healthy, and live your life, it truly isn't necessary for you to push ahead and chase a higher fitness level. It doesn't matter if you can do a pull up or ten pull ups. Or 100 pushups. Or a split. Or any of the challenging trick moves that coaches and trainers are excited to get you to try. Being able to do 10 pull ups is very unlikely to improve the quality of your life--I'm sorry to say.
But what those pull ups represent is actually incredibly important. The mastery of a challenging movement is a concrete manifestation of the work and energy that you put into yourself. Not just your body, but your whole self. It is a symbol of your ability to commit and to work hard. And while it is unlikely that doing a pull up is a skill you will need in daily life (well, maybe! I don't know your life!), the ability to show up for yourself is something you need every moment of your life.
So this leads to my conclusion about training:
It doesn't matter what you are physically able to RIGHT NOW (so don't get frustrated by your limitations), but it does matter that you continue to show up and attempt the thing you cannot do for the simple reason that, when you finally do it (and you will if you keep showing up), you will get to physically experience the result of hard work, both literally and symbolically. And, in many areas of your life, the result of your work is less tangible, so training your body is the best way to feel, see, and live the result of commitment. Training is just a metaphor for the challenges of life, and learning to show up is the only way to get anywhere. Across the board.