Well, self awareness goes a long way, so you’re on the right path. Lots of people get crotchety and cynical by focusing too much on things that are outside their control. Focus more on areas of your life that you can influence, and learn to enjoy your life for what it is rather than what it could be.
Honestly, if you’re the type of person who’s prone to this, disengaging from hyper cynical social media platforms (yes, including Lemmy) is probably another good idea.
My dad used to be super into politics and consumed rage-bait news on TV and social media a lot, especially during the height of covid. Once he unplugged from all of that there was a noticeable shift in his demeanor and I would say that he’s significantly happier and more content now.