Sayyidi wa sanadi Shaykh Mufti Taqi Usmani (Allah preserve him) said:

‘Hakim al-Umma (Allah have mercy on him) stated that the essence of all the actions (of Shariah) are sincerity (ikhlas) and willpower (himmat). Further on he said that from these two the main is willpower. This is because willpower is needed to develop sincerity. (1)
There are various methods of developing willpower.

One of them is being in the company of individuals who have (already developed) this willpower. Socialize with them. Gradually their willpower will be transferred to you.

Second method is to read about the people of (developed) willpower. This will also transfer their willpower to you.

The third mode is being vigilant about willpower. This is by setting a penalty for being negligent in omission of a good action or commission of a sin. For example, if I fail to use my willpower to abstain from a sin I will offer x units (rakat) of salah or pay y amount of money in charity. (2)

However, the method  of developing and utilizing the willpower is different for each individual.  A standard prescription can not be given to all. It is the Shaykh who decides what method is most appropriate for a specific individual. You will often stumble  if you select and act on your own suggestion. (3)’

Islahi majalis, volume 2, pages 261 (1), 268 (2), 269 (3)