Rewards/incentives

I have tried to make detailed goals for myself in the past but I have never really established a reward system so I am going to try that this time

For example.

I know I need to drink more water and less soda.  For now the plan is that if I drink water all week, than when I am at Panera with my friends knitting on Sunday I can have a soda.  I plan to eventually ease that to once a month.

I am also trying to get off fast food again and return to home cooked meals or at the very least food from actually restaurant.  Maybe I will try to establish a weekly eat out night and do everything possible to limit myself to only that one meal a week.  I also would like to try to go to more local restaurants rather than the chains.

I am once again instituting my rule that I am allowed desert but only if it includes the fruit from my CSA.  This will have to be reevaluated when the CSA ends in October.

I need to come up with some sort of incentive for exercising.  Any suggestions out there??