That's what people say when something seems simple from without. A quick remedy, a simple step, a clear route that seems evident when you are not the one walking it. The words are said naturally, almost like consolation, yet they carry more weight than anticipated.
Because occasionally it is that difficult.
Not because the work itself is unachievable, but rather because of all surrounding it. The uncertainty, the pressure, the anxiety about making it incorrectly, the burden of past efforts that did not go as planned. All of that makes something little into something that seems bigger than it really is.
"It's not that difficult" misses what people don't notice. The work necessary to get started when you are not prepared. The dedication required to keep going when motivation wanes. Only the mental push needed to stay consistent.
But there is another aspect of it.
The difficulty is determining which edition you are using.