I also find solving problems satisfying whether it is fixing something by tightening a screw or getting a query in a database to work properly.
I like being useful whether that means answering someone's question, holding the door open for someone with too much in their hands, reading a book to a child or making a thoughtful observation that someone finds helpful.
Creating something new out of old things, or just a new drawing, painting, etc. is also satisfying.
No matter your occupation or position in life I think everyone finds aspects of it that they like better than others. Sometimes when we feel unsatisfied with life currently I feel like there is a tendency to want to drastically change your life. Move somewhere else, quit your job, etc. However, I'm not convinced that is necessarily the answer, because as I said before there are always things that we don't enjoy..... but maybe instead of trying to drastically change our lives we can instead try to find opportunities to incorporate things that give us satisfaction.
I don't often have the need to do hard labor but the other day when a friend was moving I volunteered to help. Once when my Mom needed a handout for a lesson I volunteered to whip one up instead of just letting her get one offline (sure she could have just used a pre-made one but it was more fun for both of us that I made one).
That said I think there will always be times of discouragement and depression whether you are living a balanced life or not but I think recognizing what makes you satisfied and looking for opportunities to do them does help.