Motivation from within is the strongest, and requires that work be aligned with personal goals, either in developing skills or making something happen. In these conditions, I've found that I'm at my most productive no matter where - I'm working against the clock to realize my own ambitions within the many constraints of my job.

However, this could simply be a mental health thing in anyone's case. There is nothing to lose and nothing to be ashamed of by consulting a professional about it.