What about Godly Discipline? (1 Timothy 4:6-10)

If we are redeemed and united to Christ then how can we discipline ourselves?  It sounds as if Paul is saying that on the one level salvation is by grace, but now it is up to you to complete the work that has been started.  Is that what Paul is saying?  Is this how we go through life with this confidence that the Lord gives us enough grace to make it?  Or is Paul telling us something different that we need to heed?