The most important trick to being happy is to realise that happiness is a skill you develop and a choice you make. You choose to be happy and you work at it. It’s just like building muscle or losing weight or succeeding at your job. You decide that it’s important to you, you prioritise it above everywhere else, you read everything on the topic and you work at it.
Buddhism has done a lot of good work on this. I don’t think modern science offers good answers here. I think the modern world is really bad. The modern world is full of distractions. Things like Twitter or Facebook aren’t making you happy, they’re actually making you unhappy. You’re essentially playing a game that’s created by the creators of those systems. Yes it can be a useful game once in a blue moon but most of the time, you’re just wasting your time. You’re engaging in envy, dispute, resentment, comparison, jealousy, about things that frankly just don’t matter.
Happiness is internal. Work on your internal self. Realise that all real success is internal and has very little to do with external circumstances. But one has to do the external thing anyway, that’s just how we are biologically hardwired. You have to do it, you have to have your own life experiences to bring you back on the internal path.