To start, anything to keep your mind occupied. After the first part once you've broken the routine, it'll be easier. Some examples below (all of which I've found help)

• Deep clean your house. Get into all the nooks and crannies you'd normally disregard.
• Exercise, either go for a run or do some press ups/sit ups.
• Reading a book
• Organise your belongings, and have a clear out of junk
• Reconnect with friends and family, give them a call just to check in
• Have a shop around for new deals on utilities, phone, internet, etc. See if you can save some additional money.

I find its much easier to not smoke up if you're using the time you save to actively better yourself and your life.