nemathode

Don't compare aniracetam or oxi to amphetamines (or ritalin) - the former is legal and safe enough, and the latter is much more dangerous and ineffective (in terms of concentration enhancing). I would never ever recommend amphetamines nor ritalin, cannabis or other "useful" drugs, that always make you want to take more of them. All what they can give is faster burnout of your brain and state of lack of energy (also, problems with your skin, thanks to amphetamine overdose).

What OP was talking about was not psychostimulation, but concentration enhancer, something that would just reduce effects of "mind wandering" and let him do tasks that he doesn't want to otherwise.

Aniracetam and oxi do greatly reduce effects of "mind wandering", large amounts of grains and fruits give your brain very much glucose, i.e. energy to use to, coffee increases your metabolism and blood flow, and gives a slight stimulation, so you can force yourself to do task more easily.

Don't overuse coffee, though, it's effects can last from 1 to 3 days (or even more).

Aniracetam (or Oxiracetam, if Aniracetam doesn't work for you) + DMAE. Don't forget to balance your blood pressure, use venous or arterial drugs to enhance whole body blood flow (don't use drugs that work only locally). If you don't want to use blood-related drugs, then just exercise regularly (try to focus only on resistance-oriented exercises). Try to sleep on a hard bed without any pillows. Also, increase your metabolism and energy by drinking a cup or three of coffee in first half of day and eating a big (300+ grams) portion of boiled grains + a good piece of meat, but with small amounts of fat. And don't forget to eat a lot of fruits - primarily oranges, apples, bananas and pears.