That time period after marching band season when you don't know what to do with your life. It usually begins towards the end of November, leading to weight gain due to the upcoming holiday season and lack of regular exercise that one had previously.

Briefly, "the realization that each random passerby is living a life as vivid and complex as your own." Originally from the Dictionary of Obscure Sorrows, which has a lot more beautiful neologism definitions like this you might enjoy.

That feeling you get when marching season is over and you really miss it. You actually have free time now, but at what cost? It's when you really miss late night football games, and contests, and being with your band family 24/7, and sometimes you get so desperate you even miss band camp and all the hours of exhausting rehearsal.

Symptoms include excessive crying, watching past show videos, playing through old show music, and just standing on the marching field for no apparent reason.