Take more time to notice what's unfolding in your life on a daily basis. Train your brain to notice the positives, as this doesn't come naturally for most of us. Identify your accomplishments for the day, big and small. In time, you may become more aware of things that repeatedly distract you.
So what, now what? Just before you leave work, or perhaps before bedtime, take five minutes and write down a quick bulleted list of your accomplishments for the day.