The greatest negative stimuli of studying are hard to address for me, actual failure to comprehend a difficult set of problems for weeks is itself enough to make me want to give up completely at times, and the simplest ways to eliminate this would be by no longer caring about results or actually succeeding at everything I do. The first would remove most of my incentive to learn in the first place, the second I would love to do but I don't expect this to be feasible any time in the near future.

There are probably effective ways to make studying more fun that I have not really explored though... Studying in groups with other people dealing with the same problems seems to be effective but can be hard to do practically, Nicotine can be used to artificially associate actions with pleasant feelings, along with other drugs. If nicotine actually works as well as Gwern and some others suggest I may try it, but age and then financial constraints have been too limiting.