While reading another user's question about pre-thetic, perceptual faith, I was struck with a possible solution to this problem of Phenomenology's relation to effort. When Land says that it grounds the experience of effort, he means that Phenomenology takes experience at face value — allows effort to be, rather than a necessary consequence of the biological instinct of an organism (thus not something truly willed by an agent), an effort made by a willing entity. Materialism would seek to get beneath the apparent facade of a 'willing subject' and show how that will is only a consequence of biological configuration, which, in turn, is only the consequence of a material configuration.
Phenomenology expressly forbids this reduction of experience to material, biology, or even some sort of ideal, and, thus, it gives effort a reality beyond mere appearance — gives appearance(initial experience) primary reality, more.1 Phenomenology gives a reality to agenicagentic experience, an experience without which 'effort' would be a senseless term.
Edit: Removed the term 'work' from answer as well to be consistent with the rephrasing of the question.
1 I considered using, instead of primary reality, epistemological priority here, but I am not 100% sure such an assertion would be entirely accurate of Phenomenology, which may not even be related to epistemology at all — without at least some epi-phenomenological articulation as bridge. With some extension and more thorough research, the relation between observed Phenomena (the record of which would be Phenomenological) and epistemology (the rules by which we validate truth values) could be a valuable line of inquiry; hence, I include this remark.