How to write the northern character of running script

Everyone in ancient and modern calligraphy has written many kinds of northern characters in running script. The picture below shows the northern characters of the three most beautiful running scripts I found in the calligraphy dictionary. Su Shi's northern characters are one high and one low, with two horizontal lines and two slightly inclined vertical lines. The pickup of the third pen and the echo of the last pen form a left-right echo, and the whole is very elegant and dynamic. Zhao Mengfu's northern characters are different in three horizontal points. The two vertical strokes are very thick, and the two systems add aesthetics to the font, and the whole character is thick without losing strength. Qigong's northern strokes are thick and thin, light and heavy, and the flying white of the third stroke adds a bit of charm, which is more modern as a whole.