A 2% dehydration leads to a 20% loss of performance. Increase you fluid intake, especially during and after exercise.
We are made largely of water, so any lack of the stuff of life has a dramatic effect on you
Tiredness, lethargy, loss of concentration and poor performance can all be attributed to a lack of water. Try to drink 7-8 glasses a day, remembering to take small sips often-you can actually only assimilate a small amount of water into the body at once.
you fluid intake, especially during and after exercise.