I am going to put forth the radical proposition that you should not try too hard to be happy.
Instead you should seek contentment.
Why not happiness?
Because happiness is open-ended. Happiness is all about the ideal (whereas contentment is about the real).
Happiness is constantly redefining itself. Happiness is a moving target, a never-ending, ever-evolving list of wants, whims, and flights-of-fancy.
What makes you happy today, or this year, will almost certainly not make you happy tomorrow, or next year.
The quest for happiness will therefore exhaust you—and probably cause you to treat others poorly, too.
An overemphasis on happiness encourages you to look at every person and situation in your life with a critical eye.
An overemphasis on happiness is what causes midlife crises, and midlife divorces.
The quest for happiness is what makes middle-age men buy sports cars.
An overemphasis on happiness leads to that vice that the ancient Greeks called hubris—an excessive pride or overconfidence. Because when you are constantly asking yourself what would make you even happier, you tend to develop an inflated view of what you’re entitled to have.
Of course, the above paragraphs assume a certain base level of having one’s life together. I’m not suggesting that you should be “contented” with being overweight, in an abusive relationship, in debt, or unemployed.
The definition of what it is reasonable to be “contented” with is different for each individual. It varies by age and life stage. A fifty year-old would be contented with things that a twenty year-old ought not to accept (and vice versa).
The determination your reasonable “baseline” requires self-knowledge and introspection.
But once you do determine that baseline, I would encourage you against chasing happiness with too much vigor.
Seek contentment instead, contentment with what you have.
Contentment is attainable. You can rely on it. Happiness, by contrast, is a hare that, once sighted, you can chase…but never catch.