Practice strategy for meditation: A total of about 40 minutes per day is a basic adult strength dose of meditation for an experienced meditator. It is often more illuminating - and more practical - to split the sessions up. Twenty minutes, twice a day, is often very nice.
Especially if you are having difficulty taking the peace of your meditation practice into your every day affairs, you might try this (or something like it): Do your formal meditation sessions for 2 minutes, 10 times a day. 2 x 10 = 20.
Always feel free to adjust your formal practice to the needs and exigencies of your current situation. If you would like help exploring what's helpful for you, be sure to ask your teacher.