Make an appointment with yourself to clean your (insert project). Write the time on your calendar just as though it were a business or doctor’s appointment. This will make you keep the date, help you get started, and provide motivation to stick to your plans.
When you put the appointment on your calendar, protect it like you would a top priority. Don’t be tempted to cancel it when a better offer comes your way. You don’t do that to your friends or to your work commitments, so don’t do it to yourself. When you have a project scheduled on an upcoming evening, afternoon, or weekend, spend some time before that appointment considering how you’ll tackle it.