After joining a club, tap on the "Activity" tab. From there, you can tap the "Ask" button to ask for other club mates to send you hearts. When you see a club mate asking for hearts in the chat, don't hesitate to push that "send" button, it won't cost you anything!

Please note: this feature has a recharge time. You can request 5 hearts every 3 hours, and you can only send 100 hearts to teammates every 24 hours.