Win The Little Battles
Making grandiose statements about becoming resilient is not the way to do it. Talk is cheap. Winning lots of Little Battles will develop your willpower and allow you to create the behavioural change that allows you to persevere when it gets tough, or monotonous, or when it looks like all hope is lost. Getting comfortable with being uncomfortable is what makes us tough. Start with something you can do on a regular basis that is inconvenient to you. For example, spend the first two minutes of your shower with just the cold water on. Then increase the number of uncomfortable tasks and their intensity. Make mental toughness your calling card.