Reading and understanding difficult material
Definetly yes! Even if you feel frustrated at the beginning, thinking and learning about a topic has an impact on your brain. See for example Robert Greenes book "Mastery" (https://en.wikipedia.org/wiki/Mastery_(book)), where he describes the lives of various geniuses like Leonardo da Vinci and Charles Darwin. They all spent a lot of time becoming masters of their field.
Theoretical Computer Science is a very abstrct topic. I would recomend you to participate in some online class. See https://www.coursera.org/courses?languages=en&amp;query=computer+science for example. There you can do excercises that get peer reviewed by others. So you know if you did well or not.
Increase you motivation by:


Learning in groups like on Coursera.
Setting clear goals. What do you want to achieve? Get a better job? Write it down. Hang it on the wall.
Taking small steps. If you take steps that are too big, you might feel overwhelmed.