They say that going to the gym will leave you feeling envigorated and refreshed.
In many ways this is a big lie and heres why. Excersice will only give you benefit if it occurs regularly and going to the gym for the first time or going after an extended absence (as I did yesterday) will infact leave you feeling completely knackered.
This is (probably) because your body is not used to the exertion so it needs much rest after the event, ie makes you feel knackered. However if you are a regular exerciser then your body is used to the strain and afterwards will be gathering energy from fat and releasing endorphins and all that malarky. The net effect of all this is to make you feel better (mentally) and more energetic.

Of course these things will probably depend on how hard you push yourself in your chosen sport, it is always possible to go to far which will result in exhaustion. Going to this level will probably result in you getting fitter quicker but of course for this you have to pay the price of being knackered all the time.

All the words starting with ‘ex’ in this post were brought to you by a dictionary I honestly have no idea why the spelling of these words causes me so much trouble.