Bodily exercise, when compulsory, does no harm to the body; but knowledge which is acquired under compulsion obtains no hold on the mind.

Force can march a body through a task and leave the mind entirely untouched. Learning under compulsion gets performed rather than absorbed, which is why so much of what was drilled into you has evaporated while the things you chased on your own remain. Interest is not decoration on top of study. It is the mechanism by which anything stays.

If something will not stick, examine why you are learning it before you examine your technique. Find the version of the subject you would follow without being made to. That version teaches faster than discipline ever does.