Strength is not tested or demonstrated during times of ease. Rather, it is during times of adversity that one finds out just how strong he is.
God has a calling on each man’s life. Furthermore, He enables men to fulfill their appointed work. Man, however, must be strong and DO the work.
How would making your motive match the Lord's motive change how you approach the Christian life (from witnessing to praying to Bible reading and so on)?