Everybody gets jealous sometimes, even if only as a child. It's not helpful and, if you are Christian or Jewish, the Bible has a lot to say on the subject; but it is human.
However, it's all very well saying jealousy/envy is wrong, isn't it. How about some tips as to what you can do about it? Well, here are a couple of suggestions which might help.
When you find yourself envying somebody something they have but you haven't, try to think of 3 things you have which they haven't; this can include material possessions, personal attributes (i.e. talents or things you're good at; don't gloat or get holier-than-thou because you're a better person than they are), things you've achieved, places you've been etc. If you don't know the person very well, or it's somebody from your distant past and you're out of touch, just do the best you can with what you know or can remember about them. You may make reasonable assumptions, but don't overdo it.
Think of 3 things about them which you don't envy; this can include health issues, something which is a blessing to them but wouldn't be to you (i.e. a job which they love but you would hate, or a spouse you couldn't live with etc), a difficult childhood, personal struggles, something they failed to achieve. Again, don't gloat, and if you don't know them well enough to think of 3 things, just do the best you can.
These won't solve the problem, but may help you get things into perspective a bit.