Some classes are a breeze (easy for me to say, right?) and some are not. Some can be easily taken online, where you set up your own schedule so you're on target and won't miss your submission date and time. On the other hand, some classes have to be taken in the classroom. You must have that classroom interaction with the professor and at times, other students. Explanations may need to be given more than once to get the full understanding, you may need to have a one-on-one with the professor, or you may need to buddy-up with other students to get your homework done.
I have found some professors to be inflexible, tough, unfriendly, forgetful and just downright mean for no particular reason though. These are mostly the online ones. My thinking is that the ones that are like this probably just feel that they should because they have the title of "Professor". Almost all the time there is usually no particular reason to have these type of traits -- except just to say that "I'm Professor So-and-so, remember that - you student!" I can't think of any other reason and those are the classes where you pray for the semester to come to an end so you can end your dealings with the egotist.
My ability to learn at this age and stage of my life has not at all diminished. In fact, I'm a quicker learner now. Glad I'm keeping my brain "tuned-up" so that when I'm in my eighties I'm still razor-sharp. That's the plan here folks...that's the plan.