Researchers have proved that Happiness doesnt come to you by magic. Its is an end result of proper decision making.
I dont mean to deny that fact that lot of people associate spirituality to happiness. Lot of people chose a particular religion because they made a decision that this was the way of life they want to live and hence it makes them happy in whatever religious duties they perform.
Now you make investments ( whatever kinds ) they are but they involve thorough decision making and when you reap the benefits you are happy.