Second trimester

I'm in my second trimester and I have gained more weight than me and my dr are comfortable with. I feel like I'm letting myself, my baby, and my body down :-( I worked out HARD pre pregnancy and now I have no motivation! PLEASE send me motivation, I promised myself and my husband I am going to the gym tomorrow so once I start I know I'll find a comfortable routine to stick to. Also will I be okay to lift weights since I used to a few months ago?