For Christians, charity is a very important part of their lives. Donating organs and blood are also examples of charity. It is always important to realise that we received our body from God who loves us, and we have the responsibility to protect it.
Relieving pain is very Christian. Even if life may be shortened as a result of the use of pain medication, such treatment can still be ethical. This applies when the aim is not to shorten life, but to relieve discomfort.