The single most powerful process for building a new habit or bringing about a change in a habit, has been to do it once a day for 3-6 weeks. 

Of course, this isn't sustainable over a longer duration. As we pick up more things, it becomes close to impossible to do a bit of everything every single day. Because, many things are not as impactful if we do it for a few minutes a day than if we did it for an hour at a stretch.

However, smaller amounts of time spent are good when we are starting off. During this time, we are simply tuning our brains to get accustomed to the fact that we'll be doing this activity regularly, or in other words, form a habit. 

If you're struggling to make something stick, do it for even the tiniest amount of time every single day. And then count the days in a row that you actually manage to do it for. 

This is the concept that apps like Duolingo have turned into powerful habit-building loops. You can spend five minutes a day on Duolingo to do one lesson to keep your streak going. Of course, if you just do that five minutes a day for a long time, you'll realise that you aren't really making much progress. However, you're forming a habit that you can then build upon and progressively increase the amount of time you spend till you're satisfied with the pace of learning.