How to raise the level of happiness (answer-tip) (Fallout Shelter)

How to raise happiness from 50% to 75-76, I quickly figured out: put a resident in his favorite place of work (it does not always coincide with the most pumped skill)
For some, he immediately 100 and for someone did not rise in any, while trying everything possible work I
found the answer myself while I was registering to ask
It turns out to use the acceleration of the mining process without fail (rush)
In case of success, the level of happiness continues to grow
Did not use rush before and everything went well