My favourite Jet Li movie must be The Tai Chi Master.
In it, Junbao and Tianbao escaped the Shaolin Monastery after Tianbao's ambition got them expelled.
They joined some rebels, but Tianbao wanted to work for the Government, to get money and prestige. As well as power.
Junbao remained with the rebels, but not doing any rebellious things.
One day, the rebels got into trouble and Tianbao came to 'help', offering his sympathies.
He led the rebels into the Government military compound but then sprang a trap. Tianbao had betrayed them. Sold them off to the Government so that he could be promoted to a position of power.
Junbao, heartbroken, fell into a state of insanity.
This is when Junbao created Tai-Chi.
The movie is full of great martial arts action. This is certainly not how Zhang San Feng (Junbao's later name) came up with Tai Chi, but it was very entertaining.
This is by far one of my favourite pieces of HK cinema.