Everyone has to start somewhere and there is no shame in brushing up on the basics, even if you're a gratitude veteran.
1) Mind the gap - Not just the mantra of the London underground, it's also how we tend to view our circumstances -- a gap between reality and our perceived reality. It's easy to focus on the gap between our desired outcome and what's actually happening, but this often spirals into negativity. Instead focus on the good things that are happening. (Even if they are really, really small).
2) It's work - Happy people might make it look easy, but trust us, it's not! Finding the good in even the worst situations is a serious brain workout. But it's well worth your effort and will in fact save you a lot of stress and anxiety in the long run.
3) Practice, practice, practice - Even the so-called gratitude gurus slip up and fall into negative thinking now and again, but the more you practice the more natural it will seem, promise. It's only a matter of time before that grueling traffic-ridden commute turns into "an awesome time to catch up on podcasts".