Eternal happiness is heaven and you need two things to activate it.
First, you need to find eternity. You find eternity by shedding everything temporal, then all that’s left is the eternal. Roam through your thoughts and beliefs and concerns and worries, and think about each of these things, “is this just now? or will this be forever?”
A problem with doing this is that our minds, untrained, can only consider temporal things. We need reasoning to consider the eternal. A good place to start is Plato. Plato divided the world up into the concrete realm, and the realm of forms. Forms are eternal, what we see fits a form, but it won’t fit the form as time goes on. Yet the form itself will never change. Undirected, this goes in the direction of philosophical inquiry, you want happiness, so let’s consider the second thing.
Happiness is found in service to others. Whether it be through a job, or through charity work, or through mentoring others, or any of the countless ways in which we can find to help others, this is the only way to find it. Now, I know what you’re thinking,just having a job doesn’t make one happy. Well for many people would be much happier if they could hold down a job, so there’s that. The other thing is that I didn’t say having a job will make you happy, it’s serving others that makes you happy. Having something isn’t serving, serving is giving what you have away.
So you need to first, escape your temporal mind rut, a good way to do this is through religion and prayer, or meditation, but there’s lots of ways, then set yourself up in a place in society where you can give what you have, your unique gifts, talents, way of seeing things, that you can find through the above escape into eternity, and get rewarded in turn, with love and blessings, and maybe even a bit of money, from the world.