That's a complex question to answer, because the answer depends on specifics.

Do poorly or incorrectly scripted, built or used subliminal programs require extra effort? Most definitely.

Do correctly built, scripted and used subliminals require extra effort? Sometimes.

If you are using a properly scripted, built and used subliminal, it may require extra effort if you are particularly resistant to the goals of the program.

If you use a subliminal program to build muscle, for instance, and you find yourself exercising more often, did you do that, or the subliminal? That depends on how the subliminal was scripted, and how you reacted to it. It might have been either, or both.

Different types of subliminals can require different levels of effort from the user. Those designed simply to trigger arousal, for instance, require no effort. Those designed to simply change what you believe, also rarely require extra effort. Something like breast enlargement would not require you to do anything consciously, but you might need to work out to get the benefits of a muscle building subliminal - depending, again, on how it is designed and scripted.