It is important to put in kavanah in the end of the tefillah as well as the beginning. In the beginning we rise up to the highest world and there we beseech HaShem to shine down His blessings upon the world. Then we return through the worlds, bearing His blessing with us. If we awaken the divine Will to bless us, but we don't bring the blessings down here, the affects of our prayer won't be as visible or as strong. For this reason we must maintain our kavanah even after the Amidah, the Shemonah Esrei, and not just rush quickly through to the end so that we can get on with our day.
We can see this in the final part of the Tefillah, Aleinu, in which we thank HaShem that we bow before Him, King and Master of the universe, and not before powerless invented gods. If we arrive at Aleinu full of the kavanah of our prayer (meaning we brought the blessings back down through all the worlds) then we aren't saying empty words when we acknowledge HaShem's great might, rather we are testifying to the reality before our eyes.
To maintain kavanah for even in a short time during prayer can be very difficult, so I suggest a small kavanah which I believe the Rabbis alluded to: The three steps we take forward before the Amidah, and the three steps we take after the Amidah can be used to focus these ideas. Even if you didn't manage to focus until you reached the Amidah in your prayers, when you take the three steps forward, have in mind to alight through the three upper worlds, Yetzirah first, then Beriyah, then Atziluth. When you take the three steps back at the end of the Amidah, have in mind to bring the fruits of your prayers back down with you first to Beriyah, then Yetzirah, and finally Asiyah.