In my case, being good at programming was my means to feeling valued and valuable, and the sense of "I should" came from feeling useless and not needed, specifically after being forced into early retirement. (but the same pattern has been with me since childhood)
Not having a family or passion project (which fills those gaps for many people as far as I can tell) made all of this feel very urgent and threatening.
> which part you actually want to do
Which sounds like such a simple question, but I found it hard to answer. For me, it quickly turns into "what is worth doing", which is a bit of a monstrous question. I'm still trying to figure out whether this is a result of being mostly estranged from myself and the question of "what do I want" due to being so overwhelmed with trying to succeed with the external constraints and demands the world places on us.
That’s not a bad thing - just find out which part you actually want to do