How to increase will power and self-control:

1) Learn how to manage stress.

The biology of stress and the biology of willpower are simply incompatible. So any time we're under chronic stress it's harder to find our willpower. The fight-or-flight response floods the body with energy to act instinctively and steals it from the areas of the brain needed for wise decision-making.

2) Avoid temptation.

Example: If you have decided to stop smoking, do not go to the places where you find people smoking.

If you have decided not to see mobile while studying, keep your mobile far from the place where you are studying.

3) Meditation, Exercise

Practicing mindfulness meditation for a few minutes each day can actually boost willpower by building up gray matter in areas of the brain that regulate emotions and govern decision making. ... Practice once a day to train your overall willpower, and practice in difficult situations to help handle stress and cravings

Although your willpower may be fatigued in the short term, it can be strengthened over time – just like your muscles when you exercise. According to some researchers, willpower tends to be greater if you are working toward your own goals

4) Reward yourself.

It's important to reward yourself, and your team, as soon as you complete a key task or objective. ... By rewarding yourself in the moment, your brain elicits positive emotions, and increase your will power to completing the task, leading to the realization that your efforts result in a positive reward

5) Get support from others 

example: If you have decided to go for a run everyday and are not able to do so because of your low will power, then take support from others such as fix a walking mate or join a group

If u have decided not to see mobile while studying and not able to do that because of low will power, give your phone to elders and take support of them 

6) Concentration
The Importance of Concentration of Attention. Concentration means focused attention, and it has many uses and benefits. It assists in studying, enables faster comprehension, improves the memory, helps in focusing on a task, job or goal, and enables you to ignore meaningless and irrelevant thoughts