When I get a golf club in my hand, I get that feeling of wanting to knock the cover off the ball.  It feels good to put all of my strength into hitting the ball.  Just hitting the ball as hard as I can does not mean that I play good golf though.  
If you just need to relieve a little stress, then swinging with all your strength may accomplish your goals.  However, if you want to play golf well, then you are going to have to hold back on the power a little.  
One of the most frequent mistakes is to swing the golf club too hard.  A hard swing shows that you have power, but accuracy is the name of the game in golf.  
You need to relax when you are swinging.  This will help you swing easily and will help to reduce your power.  If you put your feet closer together, then you can further reduce the strength of your swing.  Tensing up will also cause you to use too much effort.  
Your center of gravity is also very important.  Keep your center of gravity the same and your head will stay still.  If you keep both of your feet in the same position throughout your swing, then your center of gravity will be stable.    
If you jerk your body then your head will move and you will not be able to focus on the ball.  This can also change your center of gravity.  It is imperative that you keep your feet planted so that all your weight will be concentrated in your feet when you make contact with the ball.  
Expending very little effort should be your goal.  If you hit the ball correctly, then it will feel smooth and easy.    
Don’t tense up when you are about to make contact with the ball.  If you tense up, your balance will be thrown off.  You want the club head to travel in a straight line to make contact with the ball.  
To help correct slicing, see how centered you can hit the ball with your club and how low you can send the ball.  If you send the ball too high, it gets into the wind and can go left or right on rough ground.  
You want to only use the amount of power that you are able to control.  The goal of the game is not power, but accuracy.  You want to be able to control every facet of your swing so that you hit the ball cleanly and it goes where you want it to go.  
The distance will come from your clean and correct swing, not how much power that you put into it.  
You want to try to gradually increase your speed during your swing until you connect with the ball solidly.  If you do not have a smooth swing, then you are pulling your hands somewhere during the swing.  Keep your head as still as you would if you had a glass of water balanced on top of it.  This will help to improve your swing and help you to swing more smoothly and fluidly.  
Swing at a decent enough speed to keep yourself from becoming tense and stiff.  Don’t swing too slowly or so hard that you feel the effort of the swing.  Stay relaxed.  
Try to keep the idea of power out of your head.  Keeping your power under control so that you can be more accurate is what counts!