Back to school was always about a new outfit. The best outfit- period. I loved school, and still do, but the first day of school was seriously about figuring out the best way to show your summer rested self to the people who hadn't seen you for a few months.
Why does that have to change when you aren't going back to school? Re-inventing how you feel about yourself is one of the best treats of all. Figuring out a new outfit to wear (out of what you already own), or trying a new class (be it fitness, academic, artistic, etc.) can make you feel revived, have something new to look forward to, feel re-born, at the time when the days are getting cooler and shorter.
Why don't we try to re-invent ourselves unless we have an excuse, like going back to school? Every so often a re-invention is most definitely needed in order to keep growing as a person. Maybe it is the thing that helps us get through a cold winter where on most days you would rather hide than embrace the challenge of the outdoors.