God is never in the past or in the future, He is always in the present. Eternity has no time, it is an everlasting "now". Many times during prayer mind can wander to past events and think about what has been done. But God is not in the past, in these thoughts. Therefore we miss Him, because we miss the present now. Likewise we miss Him when we think that we perhaps are going to better in the future. But the future is not here. Always we loose God simply because we loose the present. If we focus on God here and now during prayer, then we are with Him, with the real God. When we think about God in the past we think about an imagination. The Kindom of Heaven is here, Christ said. We should not search it in the future, but in the present time look for it in our hearts.
Constant prayer leads to focus on God in the present. When we truly focus on God we would have difficulty to sin.