Do you use a personal trainer? A coach?
Do you know what his/her credentials are?
Has he/she undergone any objective knowledge testing by any accredited agency to become certified? Does he/she actually have a college degree in the field from a reputable institution, or is he/she working on little education and a sketchy understanding of the science of fitness and performance?
Check this out. You probably would want a certified mechanic to work on your car, why not on your body?
Here is information about the accreditation procedure of the National Academy of Sports Medicine. There are some other reputable associations which offer certification, but not many. Be an informed consumer and don't be misled by scientific-sounding association names on a resume or fancy claims of degrees from obscure "institutions" that you never heard of.
About triathlon coaches, here is the information on Level I and II certification in the US, and here is information on Level III certification. Note that a Level I coach needs to (primarily) just attend a clinic and pass a written test. Personally, I'd recommend using at the very least a Level II coach - but also double-check their educational credentials and verify exactly what services they will provide before hiring them. (I counted only eleven Level III triathlon coaches in the USAT nationwide listing, so it might be difficult to find one of those in your immediate area.)
And perhaps I should add on behalf of the trainers and coaches out there doing a great job on not very much money - if you hire a well-educated genuine professional, be prepared to pay them a fee that is in line with their credentials, expertise, and time spent on providing services - just as in any other field of specialization. Fifty bucks a month doesn't buy many groceries for anyone!
Full disclosure: No, I haven't hired a coach yet. When I find one that has more scientific knowledge about exercise physiology and sports biomechanics than I do, combined with lots of success with the Masters Clydesdale/Athena athletes that he/she already coaches, and that I can afford, then we'll talk.