Possible Clues:

• The least amount
• Exercise done by lying around doing nothing all day?
• Zilch
• *Very little, informally
• Anything finished? Little following delay, oddly
• Absolutely nothing
• What the exercise regimen in 17-, 25-, 37- and 51-Across is worth?
• Exercise that's not worth much?
• FA team in pub, possibly swapping tips!
• *Nearly none, in slang