Listen to happy music. No matter how annoying they are, people like Katy Perry or Justin Biebers music can brighten your mood :)
Visit the beach ;) For a lot of people, the beach calms you down and makes you happier.
Play with pets.
Drink water. Our bodies are 70% made of water, so naturally it can make you happy.
Make a change. Whether it is within yourself, or to your appearance.. even if it just switching furniture around.. sometimes change will make you happier x
The creator of this guide has not included tools