Sweats are for lounging. They go with ice cream and the couch and made-for-TV movies. They are comfy and worn when you don’t care how you look.
Heels are meant to glamorous and are definitely not as comfy. You wear them with flashy jewelry and something tight. They change your posture and make you feel like you can rule the world.
Sweatpants and heels are meant to invoke two seperate frames of mind, two seperate occasions. So, please keep them as two seperate outfits. Do not be caught wearing sweatpants with heels!