Never compare yourself to others. That is a recipe for unhappiness. Always put the focus on yourself, and improving who you were yesterday. We may think a person’s life is what we want, but no one’s life is perfect, and they have things they want to improve as well, and I am sure they have their struggles.
You just have to remember it is their path, and you have your own path. Focus on following your path. They may have something you want, but that should motivate you to work harder to get what they have that you want, but try not to waste your time being negative, and jealous. Put your energy into helping yourself improve.
Also, remember that you are probably focusing on the good parts of the person’s life, and the bad parts of yours. There are good and bad parts to everyone’s lives. Look at both. Nothing is as good as it seems. You will get your time, just work for it, and be patient.
Psychology of Mindfulness 