Halacha (Jewish law): A couple of days ago, we spoke about how a person who is praying should make sure not to carry something in their hand because it is distracting. That is the main issue. You might have it on your mind to avoid dropping it. In a similar vein, there are two other halachot regarding distraction.
Number one: one should make sure not to wear a backpack. If you are traveling and stopping to pray, you should not wear a backpack on your back, especially if it is heavy, because it can be distracting. Its weight is going to constantly remind you, so you should take it down if you can and put it in front of you instead of wearing it. Also, it is not really proper to stand in front of Hashem that way. So Kaf HaChaim says not to pray while wearing a backpack.
Similarly, the opposite applies: if you see a Sefer fall on the floor near you, according to halacha, you can certainly bend down to pick it up while you are praying. It is not clear whether you may move over to it. Some even hold that you may move over to it, pick it up, and come back to your spot because of the concern of distraction. That is, if it is on the floor, it is going to bother you. It is going to be on your mind. It is going to take you away from your focus in prayer. We do everything we can in order to continue praying with Kavanah (focus).
So these are two halachot that follow the rule of Kavanah. One: do not pray with a backpack upon you. Two: even while praying, you can certainly bend down and even potentially move over to pick something up that is on the floor. If it is a Sefer, it is going to bother you. It is going to distract you and take you away from your Kavanah. I am going to go do a shiur (Torah lecture).