It seems to take at least two days to relax. Regardless of the situation or surroundings, I find my brain gets so entrenched in work and 'must do' thought processes that it can't let go.
One thing that I have noticed is when I perform, it instantly relaxes me. It's like a session of meditation - my mind lets go of all else besides the moment I am in and I enter a state of readiness.
I also find the lasting effects of performing are widespread. For the next few days I am clear, I make decisions easier and I enjoy life more.
So - as vacation starts - it's time to find a sense of play first to let all else slip away.
For yourself - what is the one thing you LOVE to do that makes you the happiest. Can you replicate that item on day one of your vacation? Start out right - and enjoy every moment of the time you have.
That way - you can relax.