Happiness is both a skill you can control and a habit you can develop. Happify, created by scientists and game developers, is an awesome web app that trains you to live a happier, less stressful and more fulfilling life.
Happify's activities and games are based on scientific research that suggests there are five essential skills for happiness: savouring, thanking, aspiring, giving and empathising. It's a lot like brain-training site Lumosity, but for your emotional well-being instead.
The activities are organised into "tracks" that you focus on each week. So games, for example, in the "confidence" track include things like clicking on balloons with positive words on them and listing three things you were grateful for the day before. Complete three activities to get a silver medal or five to get a gold one, and then choose a different track to continue working on your happiness. The free version lets you do a few activities each day, while the plus plan ($US4.95 to $US14.95, depending on your chosen options) unlocks all the activities.
Every couple of weeks, Happify will quiz you to measure your happiness, and the dashboard also shows your progress on the different happiness skills.
As with physical and mental exercises, working on your happiness needs to be a daily or at least regular habit if you want to see improvement. Happify's small, quick exercises might help you turn happiness into a habit, although your mileage may vary.