One thing I've found that helped is to set myself very easy goals. Walk 5 minutes, as someone said. But you can't try to trick yourself. Don't think: once I walk 5 I'll want to walk 5 more. If you do, even if you make it to 10 minutes, next time you give yourself permission to walk only 5, you won't believe yourself and so you won't do it at all. If you said 5 minutes then stop after 5. You can build up but not that particular session. If any of that makes sense.