Its good to aspire to be someone you look up to, congratulate those who had succeed. Sometimes you compare with others to look for things you want to improve on personally.
What if too much envy turn into jealousy? Anyone you see who is better than you, you in turn want to best them, overtake them because the jealous side of you tells you not to be weak and be better than them.
Jealousy is actually a deep-rooted evil within each and everyone of us that is difficult to overcome, you may need more than the strength of Hercules to prevent your own jealous personality from spiralling out of control. The problem of dealing with your own jealousy is not that direct, it can be manifested from your low self-esteem, the environment you are brought up in, frustration at your lack of achievements, etc. You will need courage to find the root cause that is triggering your feeling of jealous and you will need to accept and face the fact that because of these triggers, you easily get jealous of someone else.
You may think that jealousy is just a feeling inside you and there is no undesired actions carried out, so what's the big deal about it? It actually is a big deal, let me tell you that the terrible consequences of this vicious jealousy mindset and cycle will lead to forgetting who you really are from the inside, you lose friends, family and opportunities in life, ending up lonely in life, all because of jealousy. It affects how to react to people, how you think, what you say, so if you feed yourself with negative things, naturally negative things will come out from you.
I personally think that low self-esteem is the main cause of triggering jealousy. Maybe you are brought up in an environment where self-esteem is crushed to bits everyday or you are a victim of bully in school/work/internet. That doesn't matter because i know you are worth of every bits of you, try your best not to let external factors trigger you and all that is left to do is just fight off your own inner demon and become stronger.
We all have our journey to walk, we can look at others to take reference and learn but thats all because you have to set boundaries before these feelings turn into jealousy.