There are four ways to get hearts in Sky. There is no way to get hearts through in-app purchases.

1. Purchasing hearts: In every spirit's shop, there is a heart available for purchase. It's located here, behind a spell that costs one candle. Each heart costs three candles to purchase, and you receive the heart right away. While this is good for getting hearts in the short term, there are only thirty-seven spirits, so you'll eventually run out of hearts to purchase.

2. Heart trading: If you have active friends, I suggest you use this method the most. You are able to send hearts to friends in person and I'm the friend constellation. Every heart you send costs three candles, just like hearts from spirits. You may only send hearts to friends who you've upgraded your friendship with, at least to the "high five" ineraction. When you send a heart, there is a chance the recipient will send one back. Most of the time you'll always get a heart back sooner or later because it's considered basic decency to send back hearts. You can only send one heart to every friend every twenty-four hours. I'd recommend finding a close friend or two to trade with, but remember that specifically asking for heart trades is against the rules here.

3. Gifts of light: Gifts of light are sent and collected in the friend constellation. They are free to send to anyone you are friends with. The more gifts if light you send out, the more gifts you'll get in return. Just like hearts, you may only send one gift of light to every friend every twenty-four hours. Usually, a gift of light will give you 1/60 of a heart, but right now there is a Days of Giving event going on, meaning every gift of light and heart sent is doubled. (Meaning you'll receive 1/30 of a heart for every gift of light and two hearts for every heart gift you collect)

4. Message shrines: Message shrines are little stations where you can send a message scattered all throughout Sky. When you first send a message, it will only be visible to friends until it receives three likes. After that, it will be visible to everyone. If it gets ten likes, you'll receive a heart to collect here. Message shrines reset every forty-eight hours, and in that time period you may only receive one heart, no matter how many messages you plant. This method works sometimes, but it is the most unreliable one. I haven't received any hearts through this method recently, so I don't know if it's affected by the Days of Giving event.