Also think happy moments are unexpected, and something you can't plan or enforce.
But they can be in the little stuff from having your cats, own family and loved ones around, to a coffee once a week, to just sitting on a bench in a park, to more long term goals, like, achieving something you been working on for decades, to stuff like winning a medallion with a marathon.
When you travel you've happy sometimes unexpected moments during the day or travel.
It's a constant push of positive energy forward, where you can feel content constant.
But truly happy moments also happens like I said unexpected so when you do things out of the blue, box or impulsive almost.
Even when they aren't so impulsive as they seem, because everything you do, you did thought about it before.

Of course first of all, you got to recognize these happy moments. Label them as happiness when you are grateful for who you are and what you have right now.

Like having a dinner with some candle light with a good person from a friend, partner to even a stranger.

Say thank you for all the good stuff happening during the day.

I think if you keep sending out this positive energy, being completely aware, happy moments occur and come by, when you acknowledge them and sometimes even subconsciously when you're really in the moment.

And of course happiness could be differ from person to person but the core essence remains the same.

The danger in thinking that you will be happy when you reach or achieve this or that, means you will never be happy, because you are always your state of mind that you have now, what you are now, is what you are always.

For example if you are now happy with what you do or have right now, then you will attract more of that. By being appreciative right now already, you always will, by whatever you attract.

When you are not happy now, and expect it to be, when you've accomplished something. 
Then when you've accomplished something, you'll still not be happy, but only when you've accomplished the next best thing.

So yes strive high, enjoy the process and the view of the journey.
By being happy and appreciative right now.
No matter what happens, no one can steal your peace or joy.
You can always still choose your own thoughts, feelings and emotions.
So allow no one to steal this happiness.
So no one can break you ever, this is what you know from within.
No matter what the outer circumstances seem to tell.

From this happy place that you create, you attract all that is aligned with that.

Until the possibilities are limitless.

Exercise to say thank you already for the little things during the day, the rest of your life never stop.
From drinking a fresh tea to having a good fresh Sunday morning breakfast.

Or even a walk outside.
Or your loved ones or pets.

Thank you, I love you, I care about you.