As for you, brothers, do not grow weary in doing good. (2 Thesalonians 3:13)
And let us not grow weary of doing good, for in due season we will reap, if we do not give up. (Galatians 6:9)
Finally, be strong in the Lord and in the power of His might! (Ephesians 6:10)
The Lord is faithful; he will strengthen you and keep you safe from the Evil One. (2 Thessalonians 3:3)
I give thanks to Christ Jesus, our Lord, who is my strength, who has considered me trustworthy and appointed me to his service, (1 Timothy 1:12)
But the Lord was at my side, giving me strength to proclaim the Word fully, and let all the pagans hear it. So I was rescued from the lion's mouth. (2 Timothy 4:17)
God, the giver of all grace, has called you to share in Christ's eternal Glory and after you have suffered a little he will bring you to perfection: he will confirm, strengthen and establish you forever. (1 Peter 5:10)
God is our strength and protection, an ever-present help in affliction. (Psalm 46:2)