I often hear the excuse that there is simply not enough time to exercise consistently.  I don’t want to be insensitive. I know life can be very busy.  However, I want people to remember there are 168 hours in a week.  I am just encouraging you to give three hours committed to your own health through the vehicle of fitness.  That still leaves 165 hours to get everything else completed. 
I believe the biggest key to begin is scheduling your workout onto your calendar just like you would any other important meeting during the week.  Put yourself on your own schedule in your calendar.  Give yourself the same respect you would give to anyone else by keeping the appointment.  If you have something that truly must trump the appointment, then you must treat yourself with the same respect you would treat someone with whom you have an appointment.  That means reschedule the appointment in your calendar.
A second key that can help insure success is having an accountability partner.  This person must hold you accountable and be impervious to your excuses so that you will keep your appointment with yourself.  When you must miss or just fall back into old habits, this person makes sure that you reschedule and get the workout completed. 
The third key is that if this won’t work for you, then you need a personal trainer.  At some point you cannot afford to continue not caring for yourself.  A personal trainer can encourage, motivate, and hold you accountable in a way that a friend or spouse simply cannot.  Not to mention when you pay for something you are more likely to be consistent. 
The bottom line is you must value yourself.  Remember that busy can often be translated for caring for others so much that you do not care for yourself.  At some point you must realize that that the logical end-result of not exercising is the loss of your health and quality of life.  Instead of being able to care for others you will end up being a burden to others.  The best way is if you can discipline yourself to make self-appointments! But, if not, you should strongly consider investing in a personal trainer.  Exercise is true health insurance. 

Wishing you the best!  - Julian