I think therapy would definitely help but I think you can also do some introspective thinking. I took some therapeutic classes and they basically tell you to just let the person talk bc they just need to talk things out with themselves. One approach you can do is set up 2 chairs and go back in forth between the chairs like your having a conversation with someone else and it’s quite helpful.
For instance say your jealous over someone’s car, when you have the chairs going back and fourth you can “tell” the other person why your jealous like your talking to them and that will allow yourself to recognize why and work on it or alllow you to be more grateful for what you do have.. you can look up videos on the empty chair therapy approach if you want