My doctor just prescribed me Lexapro?

I'm about to be a junior in college and started taking Zoloft for anxiety and depression my sophomore year of high school. I eventually started taking it at night because my Adderall was causing trouble sleeping. My life got better eventually. The summer after freshman year of college I didn't take my Zoloft because I would forget about it since I wasn't taking my Adderall. That summer I started working out for the first time in four years and felt like I had a lot more energy. A few months after being in school sophomore year I felt like my anxiety was coming back and causing me to procrastinate on everything so I started taking it again only to lose a lot of my motivation to do things like study, play guitar and work out. I was very sociable but I found myself just sitting on my computer for hours even though truly inside I wanted to do all of those other things I mentioned. My psychologist at school recommended Wellbutrin because it also inhibits dopamine and epinephrin and thus helps my fight-or-flight response. I weened off the Zoloft and got home for the summer about a month ago and saw a doctor today who prescribed me Lexapro.

I've been reading a lot reviews about people losing motivation, gaining weight, etc. on Lexapro. WHAT THE HELL? I just signed up at the YMCA and started working out again! This is exactly what I don't want! What do you think I should do?