Anyone else has a honeymoon period with their medication?

Not sure how to explain this other than every time I get put on meds I have like a week to a month of good times where I’m doing better and after that I crash and fall into a bad depressive episode. For example, I was put on lexapro, I got my life together for an entire month (exercised, ate healthy etc.) and then my mood suddenly crashed and I was super depressed and having anxiety. I just got put on prozac and the first week on it was amazing, I felt a bit better in the mornings so I would do yoga, follow a morning routine and now my mood crashed again and I feel horribly depressed. I’m not sure if this is a niche problem or not but I’m hoping at least someone out there has had something similar happen.