How does someone "work their way" into poetry? It sounds painful. Neruda's language here indicates that he thinks poetry isn't just a game, but something that takes time and effort. It also makes it sound like his poetry is already there, waiting for him. Hmm, it's kind of like his suit is waiting on a chair every day, right? Both of them require the speaker to enter them before they can come to life.
the things, men, women, events and struggles constantly shaping me (17-20)
He shapes the suit, and the lives of the people around him shape him. Both make it possible for him to make art, a.k.a. poetry. The culture of his people makes him the artist that he is; without them, there is no poetry.
opening my eyes, creasing my lips, (23-24)
These people, events, and struggles that shape him also "open his eyes" to new ideas and "crease his lips" or make him speak about them. Neruda believed that art could reflect cultural and political movements, and this belief is an undercurrent of his poetry. In this poem, we can see how, underneath it all, he believes that his people are the reason he's writing. Without them and their struggles, he'd be blind and mute.