Totally focusing on the present moment is the key to concentration.
Thoughts about the past, be they positive or negative, prevent concentration. Similarly, worrying about the future keeps your mind away from the present moment. Thinking about anything but the immediate task at hand is distracting. Integrating the message that “life is now” will make it easier to keep your mind focused on the present. This attitude will help you concentrate on what is right before you.
To study effectively, we need to focus our total attention on what we are reading. To listen wholeheartedly, we need to focus our total attention on what someone is saying. To pray with all our heart and all our soul, we need to focus our total attention on the words we are saying to the Almighty.
((Life is Now: Creating moments of joy, courage, kindness, and serenity, p. 52))