I also recommend meditation. If the spiritual connotations put the OP off, focus on the mindfulness aspects. Mindfulness is really about focusing, or letting go of distractions so that you can focus.

For an easy introduction to this type of meditation, I highly recommend calm.com's five steps to mindfulness. You can find it on Soundcloud here: https://soundcloud.com/mayank-agrawal-14/sets/calm-com