Get a good night's sleep
If you don't manage to get a good sleep each night, this will have a knock on effect on your ability to concentrate.
Instead of being awake and alert, you'll feel less than 100% and it will show in how well you are able to focus on things.
In extreme cases, this may mean that you shouldn't even do something like drive a car. Ultimately it's your call on things like this and often a cup of strong coffee can get over any short term issues. But it shouldn't be a permanent solution to lack of sleep.
Learn to relax
This may sound like a contradiction in terms but being too tense can actually affect your ability to concentrate properly.
There are lots of different ways to relax, ranging from things like taking a warm bath through to full-on relaxation methods such as yoga, hypnosis or meditation. Choose one that works well for you and then endeavor to keep yourself on track with regular relaxation sessions.
You'll find that your ability to concentrate on everything you encounter comes on leaps and bounds when you do this.
Food plays a large part in our lives and what you eat affects how you feel. A lot more than most people give it credit for.
If you've every felt drowsy after a particularly heavy lunch then you'll have first hand experience of this.
But even if your food doesn't outwardly appear to affect you, chances are that if you eat a poor diet then you'll find it harder to concentrate and focus when you need to.
Cut down on junk food and sugary drinks. But don't just substitute diet drinks for the sugar laden ones. And don't move from burgers to equally unhealthy options. Take the time to read up on food and diet before making swaps in how you eat.
Take a break
There's truth in the saying that a change is as good as a rest.
It's way too easy to sit in front of a computer screen for hours on end.
Make it part of your routine to take regular breaks. Stand up and walk around for 5 minutes every hour or so. That doesn't mean just amble to the restroom and back either!
Whatever it is that you're doing, schedule in breaks. If necessary, set the alarm on your phone or put a pop-up reminder on your computer screen so that you have to at least take notice of the reminder to take a break. And don't just get in the habit of hitting 'OK' - the equivalent of snooze on an alarm clock.
Actually take that break!
You'll be rewarded with better concentration and focus.