Learn to meditate effectively. The mind is naturally a very noisy machine which wants to move from one subject to another like an unchained monkey. One must learn to restrain and discipline it if one is to achieve anything of substance and to be peaceful. Meditation for twenty minutes in the morning and twenty minutes in the evening will certainly provide you with exceptional results if regularly practiced for six months. Learned sages of the East have been advancing the many benefits of meditation for over 5000 years.
Do not let your mind float like a piece of paper in the wind. Work hard to keep it focused at all times. When doing a task, think of nothing else. When walking to work, count the steps that it takes to get all the way to the office. This is not easy but your mind will soon understand that you hold its reins and not vice versa. Your mind must eventually become as still as a candle flame in a corner where there is no draft.
Your will is like a muscle. You must first exercise it and then push before it gets stronger. This necessarily involves short term pain but be assured that the improvements will come and will touch your character in a most positive way. When you are hungry, wait another hour before your meal. When you are labouring over a difficult task and your mind is prompting you to pick up the latest magazine for a break or to get up and go talk to a friend, curb the impulse. Soon you will be able to sit for hours in a precisely concentrated state. Sir Issac Newton, one of the greatest classical physicists the world has produced, once said: "if I have done the public any service, it is due to patient thought." Newton had a remarkable ability to sit quietly and think without interruption for very long periods of time. If he can develop this so can you.