I've had a hard time being consistent with nutritional plans or exercise routines -- until I realized I had done this raising my children! I couldn't decide to feed them for 5 days and then not for 5 days -- had to do it every day, rain or shine. Now I apply that same principle to my own health.
This principle works for dog owners -- must feed/walk dog every day, whether you feel like it or not -- recovering alcoholics/devoted musicians/athletes/spiritual types -- all of whom engage in their practice daily in order to achieve the desired goal. Just re-apply this dedication to yourself!