We all have days that we don't want to do this or that. Exercise is WAY up there for most people. Yet, most of those people aren't happy with their bodies and/or how they feel.
Here's the scoop: you won't succeed at anything by doing the bare minimum or only when you feel like it! To have success, you must constantly strive for your own personal greatness which requires consistency and dedication. Granted, we're talking exercise at this moment but it pretty much is a blanket statement.
This is the only body you get, take care of it!