A lot of people in today's world don't really feel happiness on a day to day basis and if you take a stroll down the street you will quickly see that most people are just walking and thinking about all the problems in their life. We as humans tend to over think things and make a small issue larger than life instead of just finding a solution for it and moving on. If you are constantly worried about all the different things in your life, you can never be happy and nothing will ever be good enough for you.
This doesn't mean that you shouldn't work towards your goals or acknowledge areas of your life that need to be worked on. It actually means quite the opposite as pushing yourself on a daily basis and working towards your goals and destinations is one of the best ways in which you can feel happiness and positive emotions. You shouldn't let these goals define you however and you should really start appreciating the process of working towards these goals.
Most people see all the grunt work and preparation towards something as boring and they only see glory in the feat of actually reaching the final destination. If you have tried doing this however you will know that this glory is very short lived and you will often find yourself asking "is this it, is this what I worked for all those months". If you however, enjoy the whole process and see your work as a tool in which you can improve your personality and identity, you will really start to be happy while doing even the most boring work.
The next thing you should do in order to really start appreciating life is to start thinking of all the things you actually do have instead of constantly finding things that you miss. There are millions of people around the world not even having clean water and food to eat and this really puts things into perspective.
Start to enjoy every single thing in your life, no matter how large or how small it may seem at the given moment. This mindset will keep you positive and give you the strength and positivity necessary to start helping others achieve this mindset and what you will quickly realize is that helping others is one of the fastest ways in which you can actually feel happy.