From Longman Dictionary of Contemporary Englishwillpowerwill‧pow‧er /ˈwɪlˌpaʊə $ -ˌpaʊr/ noun [uncountable] DETERMINEDthe ability to control your mind and body in order to achieve something that you want to do It took all his willpower to remain calm.
Examples from the Corpus
willpower• After that, it was all willpower and the result was an extraordinary recovery.• The jersey, which was extra small, had shoulder straps that were hanging on by surface tension and willpower.• He recently kicked a lifetime habit as a chain smoker, a typical example of the famous MacSharry willpower, say observers.• Mind over matter, willpower over reality.• It takes a lot of willpower to give up smoking.• Losing weight is largely a matter of willpower.• More importantly, once we start nibbling naughty things our willpower slides down a very slippery slope.• She made herself get better by sheer willpower, when everyone else had given up hope.• Some children may be submissive to this approach while others fight back and will not have their willpower broken.• She was using willpower on us. 