In this interesting interview with Mingyur Rinpoche, he explains how to continue one’s practice once retreat is over, and how one prepares for retreat. He mentions:
First, you need to sit in formal meditation every day. It doesn’t have to be for long—perhaps half an hour, depending on your time and willingness. Consider meditating more than what you already do, but don’t promise too much. It’s important to build up the habit, whether ten or thirty minutes, because even if people love meditation, when it comes to regular practice, many do not meditate.
Some people say they don’t like to look at Facebook so often and think that it’s wasting time, but when it comes down to it, they cannot control the habit. In order to end one habit, we need to develop a new one. Building up a new habit will take twenty to thirty days. So set a goal for formal meditation that is doable in your life and keep at it—whether you do or don’t like it—and after thirty days it will become easier to maintain.