It sounds corny, but happiness is something you decide, not because of something. In all situations, you can choose to embrace your experiences and do everything you can about them to the fullest, or not. This can take an instant, and it can take a lifetime. Whenever we can't feel comfortable, we can do stuff we know further the constructive narrative of our lives. This narrative when nurtured and fed, will grow as exponential potential, unseen until unleashed on the world. The nurturing and sharpening of your own willpower, requires to leave outcomes to the higher good, trust and faith in that you've put in your part and that you continue to charge up.
I think I can sum up your point as: happiness and satisfaction are two different things. Satisfaction is fleeting, and happiness can be had anytime except when someone actively opposes us - moves us when we want to stand still or stops us when we want to go.
We're happy as long as we're going vaguely where we know we should be able to, to get what gives us satisfaction
It's a very basic principle: If someone is immobile, sitting and only resting, not doing what they're supposed to do, they may become deeply depressed and unhappy people.
If you go for your quest in life, you may become very fulfilled and happy even when failing to obtain any end goals.
There are of course no guarantees or strict rules in life, so are just very general cause-and-effects in play.
happiness = things_you_have - things_you_want
It's much easier to reduce your desires than it is to buy new stuff. Your resources are scarce and your desires infinite. If you can convince yourself you have everything you want already nothing can touch you. Write down a list of reasons to not buy the new hotness.
Stoicism has more to say on this, for example negative visualization. If you feel upset with your spouse or kids imagine them being hit by a car and dying in your arms. Car or truck? Did the car stop, or speed off? Burial or cremation? What will you say to your family, their friends? Manufacture details and explore their emotional impact. The frustration just evaporates.