How to improve sex life

I'm sorry for english mistakes. I'm brazilian and sometimes I get confused writing in english

You could try working out together if that is one issue, you'll find each other more physically attractive which may stimulate something in your sexy life.

You could simply ask him what his fetishes or fantasies are and move forward with those. Or vice versa tell him yours.

Try doing things that are spontaneous and out of the ordinary like being aggressive and making the first move somewhere other than when you're both in the bed.

I've been in a similar situation and from personal experience I found the only way to fix it is to be confident in yourself, in your appearance.

I know this is easier said than done but once I tried to see myself through his eyes and imagine how sexy I look to him I really learned to let go and the sex is incredible.

Only when you let go, forget what you look like and enjoy the moment will "mind blowing" be achieved.

Oh and some alcohol/weed/whatever helps lower your inhibitions, so that's always a good starter!