Anyone can live a reasonable life, whatever your purpose,goals or anything you want to achieve in your life is something start within yourself. life cannot be reason out if you're not fulfilling what is something you think is lacking about to yourself.
first and foremost you need to do is you need to analyze yourself what is lack, or something that is ain't attainable as you are now. it's the greatest challenge you will work for to fill in yourself.
lets say you have a good job , good life, good relationship ,we all know that everyone of us can have these but then when we have that it seems like we are not still settled on what we have . we keep still keep on chasing that something which is not attainable as of now because you might think it's something will make you happy. the best thing you need to do to achieve a great life of happiness is you need to lead yourself or commit to yourself that you are worthy enough.
second thing is you need to realize that one day you will be gone in this world , so what you need to do ? to attain something in your life that will make you happy is to accept the fact that whatever is you have right now is happiness. this will be gonna your guidelines to achieve more to make you happy and be contented . you only lived ones, but if you live in full of happiness , ones is enough, that is certain and its a universal thought you should always remembered.
embracing your being imperfect is your key to achieve the happiness you are longing for. The trials and all the saddest part of your life is just a obstacle in which lead to your unhappiness feeling however if you look into different angle you could say that it's just a nature in life.
happiness is everywhere , you just need to find peace at yourself to see this and feel this without bugging your mind . life itself is the happiness , no more , no less.