Start making progress again.
Stuck at the same level or taking a break? When you have 15 minutes a day, you need a program that just works.
Skip the drudgery.
Spending your time making flashcards instead of learning? When you have 15 minutes a day, you can’t be bothered with busywork.
Achieve your goals.
Worried that you need an immersion environment to actually progress? When you have 15 minutes a day, you can become fluent in Japanese.