There's a sure way to be happy that is taken straight out of the Stoic handbook: don't immediately flee from discomfort.
When you find yourself in an awkward, agitating, or adverse situation, sit in it for a while. Linger there just a bit longer than you normally would and meditate on the moment.
Once you do pull out of that negative situation you'll have a greater sensitivity to the seemingly small positive things that you typically take for granted. They won't seem so trivial after all.
This doesn't mean you should initiate or invite unnecessary drama into your life. You don't need to play into the extreme and put (or keep) yourself in a highly stressful or painful state just for the benefit of this exercise.
I'm referring to the minuscule things that we give more energy to than is warranted by the way we react to them. That silly situation we tried to ignore but still ended up allowing to turn our perfect day into a disaster. The awkward exchange that we fled from but had us feeling self-conscious for the next month. That tinge of hunger that so easily broke our will to eat well and led to a binge fest.
When we run from our discomforts it keeps us from learning how to manage them and they end up having more impact on us than they should. We also lose sight of just how special the small pleasures are.
It's hard to truly appreciate things that you always have at your disposal. Must we always instantaneously self-indulge?
I fast for most of the day and even when I feel the groan in my stomach around meal time I try not to give in to the urge to stuff my mouth with the first edible item I can get ahold of.
Instead of immediate gratification I sit there for a few extra minutes and then take my time preparing my food. The simple dishes I make are so much more tasty and fulfilling after allowing myself to fully experience those hunger pains.
Moreover, in any circumstance where I'm hungry but for some reason don't have immediate access to food, it doesn't overwhelm me.
What situations do you find yourself fleeing from (and inadvertently giving more power to when you do)? What if you addressed them instead of ignoring them? Lingered there instead of running?
You can easily contrive contentment out of the contrast to subpar conditions. Stay in that uncomfortable place for a couple of more minutes than you normally would, and see how it enhances your perspective.