Unless you are a Time Lord or you suffer from a very rare genetic mutation, you only have one heart, and that means if you want it to last your entire lifetime without giving up on you, you need to take care of it. Your heart doesn't get nights off, like parts of your brain. It doesn't have a partner, like your lungs and kidneys. It can't nap in the afternoons, like your digestive system. Your heart has to start working before you're even born and then keep on keeping on for the best part of a century without a single meaningful break.
Certain external environmental factors like growing up in the house with a smoker or living downwind from a cement factory can really damage your heart. You might also be unfortunate in your parentage. However, most of your heart health is within your control, meaning that your choices really matter - and the worse your genes or environment, the more crucial it becomes that you do your best to alleviate the unfair hand you have been dealt by both nature and nurture. You don't have to be a varsity sports-playing vegan with hours of time and lots of money to lavish on yourself, either: you just have to make a few small tweaks for large results. So let's see how well you know the basics of what a healthy heart looks like so you know what direction to point yourself. Good luck!