Usually, yes men have a very bad rep because they are people who cares too much about what others think of them if they say no. They are hypocritical at best and a coward-cum-hypocrite at worst!
But there is another type of 'yes men' for whom I have a very high regard. This type of yes men/women are men/women who has the courage and wisdom to say yes to life. They do not necessarily have to say yes to any particular person like their boss or their spouse. But they'd say yes to every possibility that life will bring them. They'd say yes to what most people would label as pleasant experiences. They'd also say yes to what most people would regard as unpleasant experiences, absolute failures or even tragic events. Come what may, they face life with no qualms. As such, they will have more energy than the rest of us to deal with whatever adversities and challenges that life will bring them, with zero energy exerted on being bitterness, upset, frustrated or regretful, but every ounce of energy of rectifying the problems they face at that particular moment.
The most formidable opponent is one who has every advantage to hurt us but one who is not afraid to face any consequences in the fight. The is not the man who can kill us that is most dangerous. Rather, it is the man who isn't afraid at all to be killed at all - whether he has the upper hand or not.
Be the yes man who says an unqualified yes to life come what may. Just being able to do that would itself be the reward - living life at its fullest.