I am going to assume from your post that you have decided that you don’t wish to or can’t become a parent through other means (e.g. adoption, fostering, medical procedures).
I wanted children in my 20s/ early 30s but it never happened and my husband at the time and I didn’t wish to go down the long road of IVF.
Over a couple of years, my mindset changed and I became very happy and content with my child-free life. I feel so much joy in my life that I honestly wonder sometimes if it was fate that it turned out this way!
I enjoy my job but I don’t live for it. I work from home when I am not travelling with work and this allows me to take lunchtime walks, potter about in the garden, do a yoga class at lunchtime etc. I have the flexibility and limited responsibilities that mean I can devote myself to my job perhaps slightly more than colleagues with children and am rewarded well for this (in that I have a job that people with families may not choose due to travel time). So, I would say firstly that you now have a freedom to make sure your career works for you and not feel tied to a certain job due to financial reasons, school proximity or child-friendly hours.
Secondly, I have noticed that I can do things at the drop of a hat whereas friends and family with children have to plan more in advance. This level of freedom and choice is very fulfilling, if you use it to do things that make you feel good. For example, last thing on a summer Friday I have packed the tent, stuck the bike on the back of the car and headed off for a blissful weekend of walking, cycling and pub lunches. Or a Saturday lunch with a friend turns into a drink afterwards, turns into meeting another friend who happens to text me, and later that turns into dinner with my brother who lives in town. I have nothing that I “need” to be home for and can suit myself and do what feels right and good at the time without checking or asking with anyone else.
I could list other things but I think they probably fall into the above category of having the freedom to make choices which benefit you. This isn’t selfish! People may say that but what isn’t selfish about having children? People have children because they want children. Of course you have to be selfless at times to then raise children.
At the end of the day, it’s horses for courses. The above might not be enough for some people who really want to be parents but I think of this is something you are coming to terms with, you should certainly be encouraged by my life and story.
Good luck OP!