I’m part of the “can’t study during commute” club (on bike or WFH), although my current position is fully remote.
First, think of the little time slots where you usually fit your reviews/lessons. I feel that, for me, the study slot that goes uninterrupted the most is the lunch break one. In the morning it’s easy to rush, in the evening it’s easy to give priority to other tasks or family, but during lunch time I’m usually free to do my own thing even if it’s just for 15 minutes.
I think Denzo’s tips are great, and the only thing I’d add is: find that specific, uninterrupted slot that works the best for you and focus on having a disciplined routine tied to it. Even if that’s just a daily trip to the toilet and you only have 10 minutes and your phone, stick to it. That way you’ll hardly find a reason to miss your daily minimum (even when you’re away on holidays) and can easily hold yourself accountable if you happen to miss it.
Personally, I feel that setting a very small minimum goal and seeing the rest as a bonus works wonders for my motivation compared to trying to fit a bigger, “more productive” goal into a routine that is bound to get shaken every now and then by mundane events. Having a small minimum goal rarely makes me less productive than if I had a larger one (since I feed on that “man, I’m on a roll, let’s do this!” feeling and enjoy the feeling of successfully overachieving), and also doesn’t make me depressed when I happen to miss my bigger goals for completely legitimate and unexpected reasons (which can also easily snowball into a chain of missed goals, since you already “failed” once).
Your miles may vary, naturally, but this is the system I found that works the best for me. Hopefully this information might help you find your own routine.
I’m not the original poster, but in my case (since I feel the same), I think it’s just a matter of human psychology: we remember negative events more than positive ones, and “failing” is something that sticks with you more easily. Part of me feels disappointed for failing and wants to make sure that specific kanji doesn’t fool me more than once, so my memory holds onto that kanji more. Also, it helps to re-study it while isolated, instead of in a batch of lessons where your memory can get muddy and lump several readings/meanings together.