The understudy prepares seriously for a moment everyone hopes will not be necessary.

Some preparation is done in full knowledge that it may never be used, and that is exactly what makes it valuable. An understudy learns everything, rehearses alone, and hopes the night never comes, while the whole production depends on that work existing in case it does. Readiness of this kind is thankless by design. Its best possible outcome looks identical to having done nothing.

Notice who plays this part around you, in a team, a family, a service, and say that you know they are ready. If it is you, the preparation counts even on the nights it stays unused.