I took the NASM a while ago but I think the NHE exam is more complex. It isn't necessarily harder, but with the study guide, it's much easier. The study guides are cheap and so, they're worth it because you get to take the exam three times for free if you fail the fisrt two. Even better, there is no cool down period meaning you can sign up for the next available which is usually the following weekend. In relation to the certificate, yeah, you'll get one in the mail if you pass because it's part of the process. You don't need the certificate to get a job there, you need to be able to pass the exam if the job you seek requires you to be involved with any program that has an exam (pt certification). The certificate is just want you get because you passed so it is sort of a frinch benefit. If you passed the NASM you should be ok, but I think they try to pick from the highest score and so the study guide is your best bet in getting an A, instead of a B or something without it.