This quote means that your quality and interpretation of life is only as good as how you look at it. If you look at everything with a negative mindset, you'll only find the flaws in things, but if you're able to look at things in a positive light, you will find your life is better because you would find the beauty in things.
Always remember, you can be as happy or as miserable as you choose to be, choose wisely. When I say life is only as good as your mindset, I hope you understand you have the power over your thoughts, and ultimately your mindset. Take some time to study this topic more in depth. It will change your life.