Put It in Writing
Write the exercise that you are committing to on your calendar, cell phone or email a reminder to yourself. This will keep you accountable to the goal that you have set.
Review and Replace
Review the schedule that you currently follow and decide what can be reduced or replaced with the exercise that you are committing to. Finding additional time for a new activity is difficult, but replacing an hour of Facebook or playing video games with an exercise program is much easier to manage. Do these things only on the weekends and free up some time for exercise during the week.