Productivity at work and at home. Develop habits, stop multitasking and say no more often

When you make something into a habit, doing it becomes painless and effortless. Consider your daily habits. Perhaps you make yourself a cup of warm tea right after you wake up. If you have done this for years, it becomes a habit and it is painless. If something is important to you, make it into a habit. At first, you have to do it conscientiously and repeatedly. One day, it will be automated. 
Multitasking is a waste of time. Imagine you are using a water host to clean the floor. You need to focus on one source and you need high pressure. If you split the source into a few hosts, the effect of cleaning is weakened. Give that one thing you do undivided attention. Move on after you completed the one thing.
Say no more often than yes. Pick what you agree to do carefully. A simple rule is to make "no" your default answer. Do only the most important things in life.