Love the quote collection on happiness by @seunoyebode!
Happiness is not a destination, it's something you work on every day. In fact, you can already be happy right now, this moment. You "just" have to decide that you want to be happy.
That's easier said than done. At any time, there are a dozen of problems we have to deal with. And for most of them, nobody ever told us exactly how to deal with them. We are constantly trying to figure things out on our own, often with disappointing results.
How can we be happy in the process? By shifting our mindset. By accepting that the stream of problems will never end. By treating each problem as an opportunity to learn something and to get better.
You might say: What am I supposed to learn from the experience of my dishwasher breaking down and flooding the apartment while my cat tries to jump off the balcony? Maybe it's staying calm, being patient, not letting the balcony door open.
There's something valuable in every problem. A little nugget of experience and information that will help you at some point in the future. You just have to accept it and maybe not get a cat.