The Aphorism is mainly about the meaninglessness of hate because it creates further reactions in the opponent. It is like anger increases anger. It serves no purpose except harming both, the person who harbours it and the person towards whom it is directed.
As to strengthening the will, it is the same way like strengthening the muscles little by little, pushing it slowly to exceed the limit. One can start with practicing regularity and punctuality in whatever one does. Fix a time for everything and do it regardless (unless something very important comes up). For example if you decide to read Sri Aurobindo and the Mother at a fixed time then do it. If you want to take up an exercise or learn something new then do it regardless of the challenges. The same applies with things of our nature. Make a little rule for yourself that you will not rush to act or speak without stepping back or conscious deliberation. Make a little rule that before acting on any impulse you will inwardly say your mantra 10 times. Initially you will slip but keep your resolve regardless of failures. Get up after every fall and offer the difficulty to the Mother and seek Her Strength to help you get over the impulsive movement. Slowly the will gets stronger and the mastery becomes easier.
Affectionately,
Alok Da
