1 Corinthians 15:10
But I am whatever I am because of God's unearned favor, and the favor He showed me was not for nothing [i.e., Paul made the most of his conversion by being extra diligent in his service to God]. But I worked harder than all the other apostles, yet it was not I, but God's favor on me [that accomplished it].
1 Corinthians 15:58
Therefore, my dearly loved brothers, stand firm [in the faith]; do not be moved [from your commitment]. Always do your best to work for the Lord, since you know that your labor in the Lord's [service] is not for nothing.
Galatians 6:9
And we should not become tired of doing good things, for eventually we will receive [never ending life] if we do not give up.
Colossians 1:29
This is the reason that I work hard and struggle also, using God's mighty power which is at work in me.