Have you ever spent the first week of a two-week holiday or vacation sleeping? This used to happen to me on a regular basis when I still had my job as a college Curriculum Manager. I was so sleep-deprived and stressed out at the start of every holiday that, no matter what intentions I had for how I would spend my time, I knew it was futile to arrange anything significant during the first few days - until I had caught up on my sleep and restored my energy levels.
A similar thing happened when I took my first 'retirement' and left my job at the college with a view to making my living from my coaching practice. For months, I had to take a nap every afternoon. I regularly fell asleep in the cinema. I nodded off each time I sat in the passenger seat of a car and, although I left work in June, it wasn't until the following January that I felt able to do anything that remotely resembled business development. At the time, I attributed my excessive sleepiness to my own personal burn-out and the need to get a toxic job out of my system. I've since learned that this loss of energy on retirement is more common than you would think...check out what recently retired women on Women Etcetera! have to say on the subject.