Write an encouraging note or bible verse and put it in his work bag/lunch box.
Examples: 1 Timothy 4:12, Joshua 1:9, Hebrews 10:24-25, Psalm 118:6-8, Jeremiah 29:11, John 14:27, Psalm 94:19
Tell him how much you appreciate him doing x,y,z for you or your family (or around the house). Find something different each day – even small things! Words of affirmation are so powerful in a marriage!
Pray for him! Ask him if there is anything on his heart that he needs prayers for and carve out a specific amount of time each day to do that.