Currently the gym section is bugged due to some missing triggers. However there is an easy way to fix it until we get the new version from the dev. First of all make sure that you found gym. Also it is probably better to this this as early as possible stage wise(how fat your character is).
Then:
- Save your game.
- Open the HTML file you downloaded with a text editor you like (notepad is enough.)
- Search (ctrl + f) the line "Check Weight->Check Weight". You will find multiple ones. This line has a number after it, like "Check Weight->Check Weight 3". You are looking for the line with the number equal to your character's current weight stage. She starts on 1 so depending on how many steps you passed you can calculate that.
- Below that line copy and paste "(link:"Fix Gym")[(set:$Evelynn to 1) (set:$gympass to 1) (set:$gym to 1) Done]". Then save the file (ctrl + s).
- Reopen the game and load your save. If you put the new line in the correct weight stage, you will find a new option called. "Fix Gym".
- Click it and play for one day and save your game again.
- At this point you can leave that new line there or delete it. Afterwards reopen your game and load your save. Gym is fixed. You are missing the intro part of gym but rest of the content should work as expected, easiest way to confirm is to check if you see "Work out at "Eve's Place"" option in the after work menu. You should be seeing portraits in gym too (health bar for example).