How to defend self using boxing n muay thai?

can someone teach me how to defend against attackers using muay thai and boxing? i understand how if it was taekwondo or jiujitsu coz u could grab the guy n put him on the floor but boxing and muay thai doesnt have grabbing. it'll be weird to be punching an attacker as if it was a boxing or muay thai competition. so how can i defend using boxing n muay thai?