Sometimes i forget to breathe?

So sometimes if i'm focusing on something, or sometimes when i'm not doing much at all, i'll forget to breathe. I usually don't notice until I start getting dizzy, then i'll take a few big gulps of air. If i'm with people, sometimes they point it out if they notice. am i the only one like this? Is this something serious that I should get looked at, or is it not a big deal? Even when typing this I held my breath without realising...