Sometimes external structure can help with activation energy.
Activation energy makes it hard to start tasks, even ones that you know you should, or that you want to do.
External structure can help give you the "kick" you need. For example:
Some external structure is more effective than others.
Some are like "Answer this multiple choice question in the next five minutes."
Easy to do: small task, short time frame.
If you don't start it right now it won't get done, so it's obvious you need to start now.
Some are like "Turn in this essay next Friday."
More work to do, more time, easier to put off.
"I'll do this tomorrow when I'm not as busy."
The sooner you need to do it, the more effective the external structure is at compelling you to actually get over your activation energy hump and do it.