Many of us face serious problem for concentration. We can't concentrate on our study or work & sometimes on praying too.

So if you're having this problem then always be determined to focus on everything whatever you are doing. For instance: While eating food, your whole concentration should be on the food. While watching TV you've to be concentrated on the show. These are the examples only.

To conclude I'll suggest that don't think about anything else when you're doing a particular thing. Because if your mind is busy on something else this distract your concentration & ultimately your concentration decreases.