Life is full of pleasant and unpleasant surprises, and you are aware that life is beyond your control and that you have to deal with the feeling of being out of control as well. The events that can't be predicted and the insecurities that come with them are a constant that you have to deal with somehow. But so far, only a few people have understood it, and you are about to be one of them.
Since this problem has been around for as long as humans have been around, many ways have been developed to solve it.
Father, give us courage to change what must be altered, serenity to accept what cannot be helped, and the insight to know the one from the other. - Serenity Prayer
The serenity prayer deals with the ability to discriminate between what you can change and what you can't. In yoga, we call this ability Viveka (Sanskrit: विवेक) a sense of discrimination – the ability to see the difference between the real and unreal, the eternal and non-eternal or truth and non-truth.
The art of life lies in a constant readjustment to our surroundings. - Okakura Kakuzō
Okakura Kakuzō realized that life is constantly changing, which cannot be stopped or fully controlled. The best attitude towards it is to accept it and develop the ability of adjustment.
Buddhism and Sanatana Dharma have developed a unique way of dealing with the constantly changing world and the unpredictable nature of things. Through meditation and direct insight, they understood that events in life are constantly changing and that there is no self or that they are empty. As long as you expect the world to go the way you would like it to, you will be disappointed and suffer.
The best way to deal with a changing world is to stay in the present moment without worrying about what the next moment will be like.
Washing the dishes is at the same time a means and an end. We do the dishes not only in order to have clean dishes, we also do the dishes just to do the dishes, to live fully in each moment while washing them, and to be truly in touch with life. - Thích Nhất Hạnh
The Yoga Sūtra would add to the previous concept that you must not only stay in the present moment, but also self-surrender to God. What we understand as karma yoga. In the Bhagavad Gita, Krishna advises you to surrender the fruits of your actions, which means you do just the action for the sake of the action and don't expect or worry about the outcome.
To achieve everlasting happiness, you should therefore inspect life and analyze what you can control and what is beyond your control. In addition, the attitude of constant adjustment to the current situation and surrender into "what is" builds the ground layer for further praxis. Such as giving to God the fruits of action and staying in the present moment just to be in the present.