1 Thessalonians 4:7
For God hath not called us unto uncleanness, but unto holiness.

When we try to figure out what it means to be holy, we think of many things that we do which we shouldn't. Our minds fill with 'thou shalt nots' and we promise ourselves that we will do better. Our minds should not be so filled by the bad things we have done; we should focus on the good things we can do. Certainly, the Christian walk requires sacrifice, but the benefits involved far outweigh the costs. Our focus must be on what we receive rather than what we must do without. Christianity is not turning from what we shouldn't do - it is doing what God calls us to do.