All the best servers hit the ball with immense power.
The key to serving at 100mph plus is to transfer all the power you can create in your body into racquet head speed and then into the ball.
The key to transferring power effectively is balance and timing.
Work on establishing a smooth rhythm then build up the speed gradually.
If you want to hit with more power you need to throw the ball further in front of you.
This will help get your body weight moving forwards into the court.
As your left arm starts to move up drive your left knee forwards, feel the hand and knee move together.
This will start to drive your body weight forwards into the court. It also means your legs will be slightly bent too.
As the ball reaches the top of the throw up, drive your legs up and forwards to the ball.
This will transfer power from the legs into the shot and will also give you more height allowing you to hit the ball even harder.
Work on developing your throwing action.
As you turn your body away from the court, move your elbow back into a throwing position, making sure that your shoulder is open and feels slightly stretched.
As you go to hit the ball your body and elbow start to move first, this leaves your hand and the racquet trailing behind.
To maximise power on the serve, hit the ball with only a small amount of spin.
To create this flatter, more powerful serve ensure the racquet face squares up to the ball on impact.
This is done by turning your hand and forearm out slightly as you accelerate to the contact point.
This squares the racquet face up and also creates even more head acceleration.
Make sure you have got the right grip throughout the serve as it is fundamental to how this works.
Don't waste all that power. Let the momentum carry you onto the court.
Watch how players like Roger Federer follow their serves into the net ready to kill off the return with a volley.