Due to fight a guy in a match for charity. I'm 5ft 7in and around 9st he's 6ft 7in and 19st.

I fought for a number of years as an amatuer and he has no boxing experience at all. I'm fairly confident I will be able to handle myself well enough to avoid getting hurt. He's not very mobile and defensivley as long as I stay switched on I dont expect to get hit much.

I'm sparring with big guys and and it took a few days but I can now get inside either by slipping under the jab or by feignting a punch to make them cover up and then quickly closing the distance. Problem I'm having though is producing an effective offense when I get inside into range. I get in some body shots but then I'm getting leaned on and this is draining my stamina.

Any tips ?