I believe to a large extent the internal and external motivational factors are essential to an individual's productivity. Although we cannot control all the external elements, it is important that these variables are not so altered that they result in a negative effect on the individual's performance . Some of these variables are working environment, wages, etc
The same goes for the internal motivational factors like the individuals state of mind, perspective etc if not at a level of equilibrium might trump the external motivational factors which are positive and right for optimal performance. So it's important we reconcile both the external and internal factors to get the best out of an individual in his/her workplace.