You are what you repeatedly do. Think a lot - and you become a thinker. Dream a lot - and you become a dreamer. Worry a lot - and you become a very unhappy person.
In this sense, happiness is also a skill, a muscle, and it is to be exercised, stretched, practiced. And as you practice - you get better. You find it easier to be happy in more difficult circumstances.
Now where do you start? You can start anywhere, the hardest thing is simply to start. When you first practice something new, it feels weird. It feels "against your nature". It requires intense concentration. You get tired and drift away in just a few minutes. For the first few minutes, days, weeks and possibly even months of practicing anything new, you will very likely look & feel awkward.
But hey, would your rather suck at something for the next few months or for the rest of your life?
You are what you practice. So practice what you want to be.
And most importantly, start right now.