Some people give up hope on concentrating during prayers because they feel there is so much to say and they find it hard to concentrate for so long. Rabbi Nachman of Breslov offered the following advice:
Make up your mind to concentrate on just a few pages. This in itself is not difficult. After reciting those pages, once again make up your mind to pray just a few more pages with concentration.
By using this technique you will be able to concentrate during the entire service. ~ Hishtapchus Hanefesh as quoted by R’ Zelig Pliskin