This worries me a lot

Stick with it until you reach your physical goals. You may need to act as if you're motivated until it becomes natural. Make a deliberate point of reaching out to friends or trying to laugh.

This feels more like depression to me. My body needed roughly six months to settle on GLP meds and I still notice extra naps and staying in more the day after an injection, especially after raising the dose.

Maybe switching over to tirzepitide would change things. Newer options aren't automatically better.

Not sure about reta specifically, but I've come across reports linking tirz to anhedonia, including from people I know in real life. Probably something affecting the reward pathways. My suggestion is to go easy on yourself and ease back into hobbies without forcing it, while still making an effort to keep up healthy relationships.

It might just be part of the process. All my unwanted habits disappeared and I suspect the flat feeling is tied to how that happens. I've quit drinking after more than twenty-five years, stopped using weed, and even quit biting my nails. Porn now registers as just a physical thing. I could almost join a monastery. These are big bodily changes. I don't believe it's permanent and I make myself get more involved anyway. The benefits seem worth the trade-off.

On tirz and I have some really low days too. I just force myself to do the activities anyway. Once I get going I usually end up enjoying them. It simply takes more mental effort to start.

You might find this thread useful. Anhedonia... that blaaaaah feeling.

I'm really grateful for all the kind replies and tips people sent my way. Existence shifts in big ways once you stop relying on cravings and habits. These days my energy goes toward my own needs, which feels unusual. I had stopped putting myself first.

This happened to me in the first few weeks. I couldn't face social events, and when I did go I just drank soda with lemon to pretend it was vodka. Once the results started showing I became a different person and others saw me differently too. It's only a matter of days, it all went back to normal eventually.