How emptiness of mind makes one blissful?

You might have heard Mystics, Spiritual Guru's, Saints claim the blissful state one achieves on the path to spirituality. If spirituality is giving up of desires, being grateful for what we have and emptying our minds from worries and useless thoughts, then instead of leading empty life how one becomes blissful? I had asked this question myself a couple of times and I think I have found an answer. Here it is.

Human psychology, by its nature, makes the effort needed and the impact created by happiness and sadness largely unequal. Somewhere I had read that if you had said a bad word to someone, it takes 16 good words to make up for it. Such a huge disparity, right? Similarly, the sadness would be much deeper if you lose some money (some significant amount) than the elevated happiness gained by incoming of equal amount of money. It takes good effort to reach the state of happiness and it is difficult to stay there for a longer time. On the other hand, sadness just occupies our minds in no time and without any effort of ours. All these things tell one thing. Sadness is more natural to humans and we are likely to spend more time being unhappy than happy.

When someone gets on the spiritual path, he is at peace with his past. He does not repent his mistakes or the missed opportunities or about anything that had happened with him in the past. He has accepted all of them. Similarly when he has pruned his ambitions and kept a check on them by remaining humble and thankful for what life has already given him, there are not many desires left. He would take life as it comes. This would mean there is not any anxiety about the future as well. With these two things - past and present gone from his mind, he is focused on the present. That takes away lots of unnecessary thinking. He thus has achieved emotional balance and peace of mind. His mind is comparatively emptier than a regular person.

Since sadness was more natural to humans and emptying our minds gets rid of sadness (along with happiness), what it leads to is a relieved state of mind. If having no diseases is healthy, having no traces of sadness is a blissful state. Since I have not achieved this blissful state for myself, I am not qualified to say this for sure. But I could observe and relate how things would evolve and my own sporadic experiences of a relived mind would tell me this would be it. Higher the expectation, higher the dissatisfaction in life. No expectation would get rid of default sadness of life and leads to blissful state.