So my question simply is "What is the best method to make sure you retain what you have learnt?"
Okay so I've tried learning mathematics up to where I should be at in the past. Every time though I end up stopping for some reason, whether that be health reasons, family reasons etc. sometimes not even for a long time, such as for a couple days/week. Once this happens the information seems to just drop out of my brain no matter and I have to start again.
I am only trying to currently get up to year 12 level for here in South Australia so I will be caught back up and ready to continue my university study and move onto Discrete Mathematics among other things.
Anyway I've tried the practice, practice, practice approach a while back where I spent probably 6+ months like 5 hours a day on Khan Academy.
To add to the problem I am currently an external student so teaching other people for example maybe difficult as I hear teaching is the best way to learn. Finding other people to teach that will listen would be difficult even as an internal student. I probably wouldn't even feel confident enough to teach due to a lack of understanding myself.
Anyway I'm not giving up yet, still looking for a method that might work. Sure you might argue why waste time asking this question, go do problems and practice more but as I said that doesn't seem to work exactly. I don't have this problem with programming for example so I don't know what is wrong. Plus once I'm back studying at university I doubt I will have enough time to dedicate to just doing problems everyday to make sure the information stays fresh in my mind.
So yeah any help is appreciated (hopefully I'm posting in the correct stackexchange site...), also hopefully not too specific to my case or something too, which I just realised might be a problem...