How do I tell people that I am having fun or How do I actually enjoy something?

English is not my first language so please bare with me.

Im not introverted or feeling emotionally drained, but for a few years I’ve realized that I find it very hard to understand how people truely enjoys something like hobbies or things that are called fun.

it happens anytime even if I am with my family or close friends, and I don’t really mind going out or trying new things. It is just that I have to process what I should do nonstop. I haven’t discovered anything that I really enjoy yet, even if I always try out new things to relate to my friends and family.

for example when I hang out with my friends, go to special dinners, concerts, I keep on thinking about what kind of expression and reaction I need to make to seem like I am enjoying or being entertained.

But I also do think this is a common experience, because I know some people feels sometimes they need to act like something or else it will ruin the vibe.
cause there is no way EVERYONE at the same place is focusing on something and truely having fun right?

I am also curious about what they feel when they cheer or clap for people, like they are very happy, for example in like sports events or concerts. Do some people actually enjoy and feel happy or are they just clapping and cheering because they are forced to?

I am asking this here because my awkward reactions are very visible and even my parents and friends had been asking if I am mad or tired since a few years ago, and I never was. Thank you sm for reading :)