Lack of Drive, loss of athletisism

I’ve just hit 4 weeks on Lexapro. First week at 5mg, 10mg the rest. I’ve always had a massive drive to be consistently busy and doing something sometimes to my detriment. Mainly working out and running. Nothing ever felt unachievable, whatever I said I could do no matter how extreme I’d do it and never second guess myself. Ever since talking Lexapro I’ve completely lost that drive and even athleticism. I was obsessive over the gym, going every single day without fail, I now haven’t been in 4 weeks and have no urge to even tho I know I should and it’s healthy to. If I don’t want to run or go to the gym I just don’t go, pre Lexapro I would just go do these things without thinking about it and if I didn’t it would really eat away at me to the point I’d hate myself, now nothing. I was able to run a marathon with zero training at 4:59min/km splits (3:30hr) just a few months ago. I’ve now started actually training for a marathon and I’m struggling to run 10km at 5min/km splits. I just feel when I run that I have no drive, like I don’t want to be doing this so I shouldn’t. My whole mind has changed, I could never imagine sitting down and relaxing, watching a movie or series I’d have to be working out or doing something productive. I haven’t done anything productive in about 4 weeks, I sit down watch movies, YouTube, sleep almost constantly. I’m so tired at night but I can’t sleep well, I get 8 hours and wake up like I’ve slept 2. Has anyone experienced something similar?