for some reason my sim always goes naked during working out

@i2nblf2640ki 

It sounds like you have the MCCC WooHoo module installed and have nudity enabled for exercising. So, check your settings if you have that module and change it so the sims don't.  Other mods will do it too, so you need to check those settings as well if you have any that alter how sims dress for various things.

Hope this helps.