fight them with your legs: One of the most fundamental aspects of Jiu jitsu is it's philosophy of always seeking to match your legs against your opponent's arms whenever possible. All the best positions and submissions in Jiu jitsu involve you connecting your legs to your opponent's upper body to take advantage of the fact that the human body has a basic asymmetry between upper body strength and endurance versus lower body strength and endurance. If you can consistently match your lower body against an opponents upper body you'll have a great advantage even when you're smaller than your opponent. Make it your mission to always lead with your legs and you'll go far in this game!
