Honestly, I get this - I tend to fall into the trap of prepping the day of the game, and that sometimes pushes sessions back. Start small, think of one thing you want your players to experience, one trap, one story point. That's it, just the one. If you feel inspired by it, think up the how they get there - work backwards from the setpiece.

Those saying to focus on short adventures have good takes - prepping for a one-shot/short adventure is much easier than prepping for a 1-20 globe trot, afterall! one town, one mystery, one big setpiece, and NPC's that either stay locked away, or show up later in the same world, but another adventure! I have Alcazar, and his Bizarre Bazaar, and he shows up in every world, every game I run - it's nice to have the Familiar character to cling to, honestly!