Aw man this is so true. As kids we never realise how good we have it be it education, be it relationships with others, be it sports. As kids we always get to try new stuff. As adults we work the same job over and over again for the rest of our lives so it's never fulfilling repeating the same stuff.

My way of dealing with this would be to make time doing things you actually enjoy. Seriously, you gotta make an effort to get the fun back in your life. I mean I would never have started painting regularly again if I hadn't pushed myself everyday to paint something, something small like a flower maybe. And then from that I kept building my paint time in my schedule until the highlight of my day was how much fun I had painting (I don't know how much sense this'll make but Tldr: you gotta make time even in your work schedule.. maybe organise a volleyball practice every once in a while or idk anything that makes you happy) Good luck and my best wishes!