This is the kind of thing I think about all the time.
For instance, sometimes he needs to be encouraged to walk on his own and sometimes he needs to be carried. We don't automatically carry him every time, and we don't automatically tell him to quit complaining and walk every time either.
It depends on so many different factors: How late was he up last night? How hungry is he? Are we trying to conserve his energy for tonight or spend it? Do we really feel like carrying him or do we resent it? Will his dirty shoes ruin our clothes?
Whatever the situation is we are honest with him about our rationale for carrying him or making him walk.
In this case it was dad's idea and it was fun!