Hi, my ole man and I can both sympathise there! I am trying to teach myself the basics of 5 string banjo after years of playing guitar, and he has taken up keyboards just this year having never played anything before.
His teacher has told him to practice small amounts often and says this works best because the brain can't process more than about 7 or 8 new bits of information at a time. So it makes sense to learn new material in small chunks. The theory goes that if you learn it in 8 bit chunks (i.e. about a couple of bars at a time) eventually your brain proceses each chunk as an integrated whole. Then you can build these building blocks into a full tune.

I hope that you reach you breakthrough, cos music should be more about pleasure than pain!