Real happiness isn't linked to anything, or anyone; only to Allah. It's when you can be happy for no apparent reason, so much so that you beam!
Real happiness is something you feel all the time. It doesn't come and go when things happen, like the happiness you get from things like winning a prize, or getting a new thing. That kind of happiness just goes away if you lose or break the thing. Some people keep waiting for happiness, because they think they will be happy when they finally get the new toy they wanted, or pass their exams, or some other event happens. But when it happens, they still aren't happy and so they wait for the next thing. You don't have to wait for real happiness, you can have it now, because the things you are waiting for are not what are going to make you happy.
Being happy, all the way, deep into your heart, no matter what you have in your life, or don't have, is a very special feeling. It can only happen when you are at peace with yourself and you are passing your days, doing things that Allah loves (or doesn’t dislike) and shines down his pleasure on you, for doing. It's as if the happy feelings that you are having are actually Allah's love, shining through all your insides, with no negative thoughts to spoil it. Learn how to deal with your negative thoughts, worries and bad expectations, so that they don’t get in the way of your happiness (see below).
Feeling Allah close to you and connecting to Him can make you feel real happiness. That is all part of having a happy mind and heart. If you have a clear mind and heart, you can even grab this happiness at times where you would have thought it's hard to be happy, by turning your thoughts to Allah right in that moment, talking to Him and feeling Him watching you, with love.
There are some things that you should beware of, because they can get in the way of you being happy. They are happiness destroyers, for example, wanting things you don't have, jealousy and other negative thoughts. On the other hand, there are things that can help you be happy, such as being in the moment, connected to Allah and yourself.
Below is an example of how to overcome one kind of happiness destroyer. You can go through lots more, and learn the things that make you happy in our Young Muslim's Mindful Book of Wellbeing.
Thanks for reading. Be happy!