It’s a problem if you are saddened because of what the other person has, be it talent, money, posessions, or whatever. If you would simply** also **like to have what the other has and are willing to work to get it, there’s no problem.
Sinful: Your new car is just what I wish I had, and I’m angry and upset because you have it and I don’t. I would steal it from you if I could get away with it. I can’t get it out of my mind and it’s ruining my life.
Not sinful: Your new car is just what I wish I had, and I’m happy for you. I decide to start saving up to get my own. The goal of getting a similar car is just one part of my full life.
Sinful: Your drawing talent makes me upset because I don’t have a similar drawing talent. I am angry with you because of it and sulk frequently. I fantasize about ripping up your drawings.
Not sinful: I admire you for being able to draw better than I can. I decide to take a class to improve my skills. If I never get as good as you are, it’s OK, because I have other talents and abilities. You glorify God by your drawing and I by my singing. I thank God for His goodness to you in drawing and to me in other ways.
