Tip #1: Visualize The Process, Not The Outcome
Visualize your efforts/actions as opposed to the end result.
Watch yourself working out or walking around the park.
Tip #2: Visualize From the Third Person
Have someone take pictures of you doing the new actions, use them in your visualizations.
Tip #3: Be Optimistically Realistic
Tip #4: Make a Step-by-Step Plan
If your goal is to work out more, then the first step in the plan will be to get off the couch and stand up.
Tip #5: Publicly Declare Your Goal
If you're not willing to declare your goals then chances are you are not committed enough to actually get anywhere. If friends and family are not supportive of your declaration it is time to widen your circle and find some new friends.
Tip #6: Track Your Progress. In Writing.
What gets measured improves.
Review your progress weekly, you really have gotten somewhere different.
Track the effort.
Track the accomplishment and the rewards granted.
Review the history when you need a pat on the back.
Tip #7: Reward Yourself
Rewards for the actions towards the goal, don't hold back rewards until the goal itself is achieved.
My mind goes straight to food so I need to think of activities as rewards (as Stever suggests.) Experiences make us happier than things so use special experiences as rewards.
Make a written list of rewards.
References Visualizing for Results, Part 1, by Stever Robbins. Visualizing for Results, Part 2, by Stever Robbins. End Procrastination with Action Days, by Stever Robbins.