Before the US entered WWII, it was necessary for a group of US military advisers to learn Mandarin in a hurry.
The group went half-way around the world by slow boat taking 35 days and then over the hump to China with Hockett managing their Chinese instruction all the way. When they finally arrived the officers were using a respectable amount of colloquial Mandarin and were able to carry out their training assignment.
Language Log: The Chinese episode
See? It just takes the right motivation to learn Chinese. Even a jackass can do it.