Comparing ourselves to other people can be something that pushes us forward. However, unless we're really secure in who we are, it can be something that piles pressure on us. When we look at others and only see the ways in which we're not as good as them, it can affect the way we think of our own value. Comparing our looks, exam results, families or social media following to other people's can just increase our feeling of not being good enough. We see this in the story of King Saul and David, when comparison led to jealousy that ruled Saul's life.
God created us all unique, with different gifts, skills, appearance and, most importantly, purpose. You were created for a purpose that is different from your friends', and the more time you spend trying to be like others, the less time you have to fulfil the purpose you were made for. Don't get so distracted by someone else's race that you forget to run your own! It's about beating your 'personal best', not competing with others.
Key bible verse
The tongue has the power of life and death,
and those who love it will eat its fruit.
Do not let any unwholesome talk come out of your mouths, but only what is helpful for building others up according to their needs, that it may benefit those who listen. 30 And do not grieve the Holy Spirit of God, with whom you were sealed for the day of redemption. 31 Get rid of all bitterness, rage and anger, brawling and slander, along with every form of malice. 32 Be kind and compassionate to one another, forgiving each other, just as in Christ God forgave you.
Do not repay evil with evil or insult with insult. On the contrary, repay evil with blessing, because to this you were called so that you may inherit a blessing.