Jodi, why can't you keep and maintain a schedule? I envy you in the sense that you don't have a schedule to keep and can stay at the gym for 5 hours if you like.
For each day of the week, map out the hours for work and for play. Do it differently for each day. For example, on Monday, you get to wake up till 9 am but on Tuesday, wake up time is 7 am. Etc, etc... I schedule different things for each day so that my work will not become montonous.