Live in the present, not the past or the future. The past is over; learn from it and let go. The future is not yet here. Plan for it, but do not worry. Worry only wastes your time and energy.
The Vietnamese Buddhist monk Thich Nhat Hanh describes enjoying a good cup of tea. You must be in the present moment, mindful and aware, to enjoy the tea, to savor the sweet aroma, to taste the flavor, to feel the warmth of the cup. If you are ruminating about past events or worrying about the future ones, you will look down at your cup and the tea will be gone. You drank it, but you do not remember, because you were not aware.
Life is like that cup of tea.