how old are you, in non professional cricket that is serious heat (pace), bowling fast is pointless if you cant move the ball in my opinion...
So alot of speed and endurance drills a lot of interval sprinting, regular beep tests,
And alot of muscle training especially focusing on the back,shoulders,chest, core and legs (just about everything).
As a fast bowler you want to be lean not bulky so with muscle training you need to be doing a lot of reps (20) on medium weight.