The four things you should build into your breaks to maximize their impact on your attention:
Fuel: Boost your energy with water and food. Drink some water. Eat low glycemic foods such as nuts and beans, which release energy much slowly.
Attention: Attention is of two types: focused, intentional attention and meandering mind-wandering attention. If you have been focused, in your breaks you should de-focus. If you have been staring at your screen, turn away( switching to Google, Twitter and Facebook gives the brain no chance to recover).
Movement: If you have physically passive during your period of activity, move. Walk, do some stretches, climb some stairs. Anything that puts your body into motion and makes you breathe deeply.
Emotion: Change your emotional tone. Use music, conversation or activity to change your vibe.