There are no mistakes in life. Even things we realise we could have done better aren't mistakes but lessons.
You don't meet people by chance or go to certain schools by chance. There's a reason for every single thing that happens in life, even being born in a certain place has some reason behind it; and it is our duty to try and find out the reasons for the things that surround and happen in our lives.
Nothing happens to us without a reason, either good or bad. It happened because somehow and someway, we need it. If we don't find out the reasons then we would have lost something really vital in our life and we will not be complete until we fill up the space that loss has caused.
Everything in life has it's purpose, no matter how bad it seems, it has a reason for being. It's just like the piano and it's musical keys, they all have a purpose. Ordinarily the bass key sounds worse than the treble but when used properly it'll sound as good as the treble and even the treble key if not used properly can cause great discomfort to the ears.
The same goes with everything in life. There's a purpose and a reason for every single thing and if we can find the purpose we can turn even things that seem horrible into beautiful things.
So, we should all try to learn the reasons for the things that happen to us in life; put things into their proper use. If we do this, things won't ever seem bad because even the so called bad things will have their good use.