Here is a nice table of words that end in –up. Some of these nouns are hyphenated, and some are not, according to the AP Stylebook. When they are used as verbs, they are always two separate words.
Hyphenated Not Hyphenated
Stress Management Tip of the Day:
While leading and explaining stress management to an audience, a young lady confidently walked around the room with a raised glass of water. Everyone thought she was going to ask the ultimate question, “Is this glass half empty or half full?”
But she fooled them all. She asked: “How heavy is this glass of water?”
Answers from the crowd ranged from 8 oz to 20 oz.
She continued, “The absolute weight doesn’t matter. How heavy it is depends on how long I hold it. If I hold it for a minute, that’s not a problem. If I hold it for an hour, I’ll have an ache in my right arm. If I hold it for a day, you’ll have to call an ambulance. In each case it’s the same weight, but the longer I hold it, the heavier it becomes.”
“And that’s the way it is with stress,” she continued. “If we carry our burdens all the time, sooner or later, as the burden becomes increasingly heavy, we won’t be able to carry on.
“As with the glass of water, you have to put it down for a while and rest before holding it again. When we’re refreshed, we can carry on with the burden, holding stress longer and better each time practiced.
“So, as early in the evening as you can, put all your burdens down. Don’t carry them through the evening and into the night. Be like Scarlett O’Hara in Gone With the Wind and worry about them tomorrow.”