You really want to be focused when you are playing poker, even online poker. Keeping your mind on the game means that when it is your time to act, you can act in your best interests. You want to be on the proactive side as much as you can, putting everyone else on the reactive whenever possible. The funny thing is, there are times when distractions really help your game. Playing poker on the Internet gives you the ability to modify your environment to your hearts content, which mainly means eliminating distractions while you play. You don't want to have to run to keep your bisects from burning when you are being pushed all in on a gut shot straight draw. However, keeping your mind busy is important, because if you let yourself get bored you will start to make mistakes.
Many an online poker player will tell you that they started loosing money because they got impatient. After hours of folding every hand they got on a bad card run they will start playing anything, just to play, and chase their way to being broke. If you can provide yourself with just the right kind of and right amount of distractions, you can keep this from happening. Playing multiple tables might help, but there are other ways to do it, and you may not be at the "multiple table level" of play, anyway.
One great way is reading a book. Keeping your sound turned up, you will hear when the dealer is passing out new cards, indicating you need to look at the game and decided if you are in the hand. If you are, set the book down and pay attention to the game. If you fold, go back to your book. Browsing the Internet is another option, as is balancing your check book or anything else you can do on again, off again. Keep your mind busy while you are not in a hand, and you will be refreshed and focused when you are.