Probably no feeling is more discouraging and emotionally draining than that of helplessness.

The belief that there is nothing one can do, much like a person stuck in quicksand.

There is a certain type of helplessness which strikes me as being the worst, since it is self-inflicted and thus avoidable.

The term for it is 'Learned Helplessness' which was coined by the psychologist Martin Seligman. 

Essentially, it means a psychological condition where an individual feels powerless to change their situation due to a history of uncontrollable negative events, leading to a lack of motivation and resignation even when change is possible.

There is an old saying, 'Whether you think you can or think you can't, you're probably right.'