IDL how it seems to take just a few months to undo years of fitness progress

I got a minor injury in january and it's really slow to heal. I have to avoid any upper/middle body exercise or any strenuous cardio until it's completely healed. otherwise it aggravates it (I did try to ignore doctor orders at first but quickly regretted it). Basically I can only do light stretches, moderate leg exercises, and walk.

I was in great shape at the start of 2026. I wasn't athletic as a kid so I worked hard for the past few years to progressively increase my strength and endurance. I ran, hiked steep mountains, did advanced pilates classes. I was finally proud of myself.

Now? I get winded climbing one flight of stairs. I need to sit after standing for too long. My muscles are soft. I feel weak. AFTER ONLY 3 MONTHS. It just feels unfair.

Please tell me something reassuring like that it will come back faster than the first time I got into shape 😅