Train your mind to be non-worrying, non-frustrated and non-suffering. And then feel the difference. Non-worrying does not mean that worries will not arise; it means you won't pick up a worry and give it any attention or power. Non-frustrated does not mean inaction or resignation; it means you will not feel defeated when your efforts to fix whatever you want changed in your Life repeatedly come unstuck. And non-suffering does not mean you are free from pain; it means you have learned to co-live with extreme pain by choosing to not ask 'why' or 'why me'. Now, when you are non-worrying, non-frustrated and non-suffering, you are happy. Simple.