It's hard to come back from vacation and get back to "real life". I actually just posted somethign on my blog about about needing to get my act together - not from a vacation, but from just regressing into negative ways to deal with stress.
One day at a time is the only way to do it. You know you can - you have in the past.
Just concentrate on today, right now. You can deal with tomorrow later. In fact, you can even deal with this evening later. Just here and now .. you can be on plan.