It's not rocket science - but it is a tried and true method of committing to something. Scheduling your workout in your calendar is essential to success. Pick a time of day ( and day) that you know you have time to get it done. Write it down in ink, or highlight it as a priority in an electronic calendar.
If you work out better in the mornings, that's when you schedule it, with enough time to get done without other things crowding out your appointment with your health!