Being a Christian is not necessarily a walk in the park. While it begins with the new birth Jesus spoke about with Nicodemus (John 3), it is the starting point of a lifetime of setting Self's will to the side, in favor of fulfilling Christ's will.
The remainder of the Christian's life should be lived out from there and it must be lived for Christ. The reality of the cross, what it means and how it works itself out in the daily life of the Christian should constantly be at the forefront of all our thoughts and deeds. The Reformers thought it no small sacrifice, even giving their lives for their Lord. How can Christians today do any less?