Re:I would recommend some exercise (Score 1)

I completey concur with above, i used to have the same problems with concentration and was heavily addicted to caffeine. I decided to quit after getting nasty headaches without having caffeine for a day and was getting horrible stomach cramps which my doctor said was attributable to the high amount of caffeine i was ingesting. Quitting caffiene majorly helped my concetration also i don't feel so tired all the time aswell( i don't get it either). Changing my diet from 80% fast food to lots of fresh fruit/vegetables and drinking around 2 litres of water a day helped my concentration aswell.