Case in point: my exercise schedule for the last several weeks.
Week before Thanksgiving: 4 exercise sessions (the most I've done in a long time!)
Week of: One exercise Class
Week after Thanksgiving: 2 exercise classes
First full week in December: 3 exercise classes (back on track!)
This week: 1 class, if I'm lucky, in addition to my feeble attempts to squeeze some kind of activity into my daily schedule.
I wish I was better about exercising regularly. After all, it is important to maintaining good health - and sanity! But when I add in all my other responsibilities - husband, 2 year old son, full time job - and the other related facets of these responsibilities (maintaining a home and family budget, finals followed by a 10 day minimester, job applications, and other professional responsibilities), I find that I just can't put my all into everything. So I try to prioritize and understand what is most important for the week I am in. This week, it was class prep and job applications. Next week, it will job applications and holiday prep. I will get my exercise in when I can by doing a few simple exercises while my son naps and attending the Saturday morning exercise classes, but I beyond that, I can't worry about what I can't do.
As long as I keep my priority list for the week relatively short (1 to 3 items), I can usually achieve my goals and feel like I've accomplished something each week. But it can be a challenge to keep my priorities in check and avoid stressing about all the other items on the to do list that have to fall by the wayside.