Un-Manly

This is not the first time this has happened, but my wife has been getting up with our baby every night and has been chasing our toddler around all weekend while she has been potty training.  So, why is it that I am the one who is exhausted and complaining about how tired I am?  I'd like to think that I deserve it because I've taken on extra responsibility with the other two during our toddler's potty training, but even then I'm realizing that I do not have the physical or mental stamina to do all that my wife does. What's worse, my wife's had a cheerful attitude the whole time.  I'm not sure whether that is because she finds it easy and enjoyable or whether she's just patronizing me because she thinks I'm pathetic.