Do we only do things we want to do?

[Belacqua]

So, this is just a bit of a thought I had while literally brushing my dog. If it seems dumb, uninteresting, etc etc, I apologize. I've just been wondering about what 'wanting' to do something means. We've all heard the old 'sometimes in life you have to do things you don't want to do' piece of advice from well-meaning grandmas, right? But I wonder if that's actually true. 
If we think of 'want' as something we do because we want the direct enjoyment or satisfaction derived form it, then yes, we often do have to do things we don't want to do. But if we think of it in a sense that we 'want' to avoid something, then indirectly we 'want' to do something else that's going to result in the avoidance of the thing we actually want to avoid, right? 
For example, I don't like to learn about chemistry. So I don't really want to do it. But I had to learn about chemistry in school. If I hadn't gone to my required chemistry class, I'd face reprimanding, punishment, suspension, expulsion, etc. I wouldn't be able to officially graduate from high school, and so I wouldn't be able to go to college. Those are all things I 'want' to avoid. Going to chemistry class = avoiding that. Therefore going to chemistry class = ...something I 'want' to do?
According to this logic, we only ever do things we want to do, and we do not, actually, have to do things we don't want to do. 

I have a strong feeling this is a pretty incoherent and illogical way of thinking, but can't really put my finger on where I'm going wrong. Thoughts?

Because we are just animals who live in a society, and not rational angels, we don't have to make sense.

It's perfectly possible to want opposite things at the same time. I want to chase all my desires; I want civilization to control things so I'm safe. I want to get the benefits; I don't want to put in the effort. Etc.

So we balance the different wants. But that means giving up on some of them. Which means that even if we fulfill a lot of them, we will still be miserable. Oh well.

This was the TL;DR version of Freud's Civilization and Its Discontents.