Most humans are never fully present in the now, because unconsciously they believe that the next moment must be more important than this one. But then you miss your whole life, which is never not now.
Always say "yes" to the present moment. What could be more futile, more insane, than to create inner resistance to what already is?
Surrender to what is. Say "yes" to life -- and see how life suddenly starts working for you rather than against you.
Why does the mind habitually deny or resist the Now? Because it cannot function and remain in control without time, which is past and future, so it perceives the timeless Now as threatening. Time and mind are in fact inseparable.
Wherever you are, be there totally. If you find your here and now intolerable and it makes you unhappy, you have three options: remove yourself from the situation, change it, or accept it totally. If you want to take responsibility for your life, you must choose one of those options, and you must choose now. Then accept the consequences.
-Eckhart Tolle "The Power of Now"