Many cadets enter Starfleet Academy with high hopes, boundless aspirations, and a plan to excel in their field wherever possible. The vast majority are successful, but very few seem to give consideration to what happens after their time in Starfleet, after their career has reached its peak.
It’s well into the 25th century (or even the 26th). Your character is a captain, or perhaps even an admiral, and for whatever reason, they have decided to finally retire from the active fleet. They are still in relatively good health, and despite technological advancements and the usual political and social machinations that have always presented threats the the United Federation of Planets, our great civilization has enjoyed an unprecedented period of relative peace and calm. Without the weight of those pips, they are free to do what they will in a galaxy seething with opportunity.
How would they spend that time? Would they focus on family, settling down to be among loved ones in waning years? Would they explore on their own, seeing parts of the galaxy they hadn’t been to during their tenure in the fleet? Maybe they’d consult for Starfleet, or teach at the Academy. Or perhaps they’d enter the private sector- leaving Starfleet might not be the end of a career.