On Pinterest, you can:

Work on a DIY
 Also known as, Do It Yourself, DIY projects are a great way to find out how good you are at something you never knew you were good at without getting assistance from professionals. You might ask, how does this help with mood improvement? Try observing what happens when you are done; you get a feeling of accomplishment which makes you proud of yourself and pushes you to let the whole world know.

Find a new hobby
Pinterest is a great way to discover new activities to try out in your spare time. The good thing about it is, once you find what you are looking for, you can decide to pin it (save it), meaning, you will not have to worry about ever losing what you just found or going through the hustle of searching again.
But here is the best part: it allows you to create boards which allows you to visually curate saved items pertaining to the same topic to make finding these items easy for you.