Yeah I've had those too.. like some part of me felt too tired within the lucid to put out the effort to do anything with it. Then I wake up and feel like "What was I THINKING?!? God what a waste." You have to remember that the cohesive flow is way off in dreams, even in lucids. The best way to combat this in my opinion is perform SOME task in every lucid, regardless how small or mundane it may seem. Exercise those lucid muscles