There is more heroism in self-denial than in deeds of arms.

Courage that nobody sees is harder to sustain than the kind that comes with an audience. A dramatic act takes place in a moment and carries its own momentum; going without something, day after day, for reasons only you know, has no momentum at all and no applause to keep it going. That is why most people find the second kind heavier. It asks for the same resolve repeatedly, and never confirms that it was worth it.

Notice where you are already doing this and give yourself the credit you would give someone else. Then pick one small refusal and keep it for a fortnight. The practice transfers.