You're right, pay check is one of the reason to work, and also one of the condition to be happy at work. But there is others, like: - work/life balance. - autonomy/work load balance. - acknowledgement of the work done by the company. The manager or else. - clear vision of what the company is doing and the role you have in it.

There is a lot more, and a lot of companies don't provide that to their employees.

There is a nice startup[0] that tries to bring happiness at work to other company. What is in for the company ? Better productivity of the employees and less turn over.

[0] Wittyfit. Full disclosure: I worked for them. They are not alone in the field, but I think they are the only one to have a scientific research based product.