I gained it so
climbing slow
The poem starts past-tense—she's already gained it. Everything in stanza one is backstory about the climb.
strategy
Military word. She's treating desire like a campaign, complete with tactical planning.
I said I gained it
Notice the shift: "I gained it" becomes "I said I gained it." She's already doubting her own opening line.
contented beggar's face
Paradox—beggars aren't usually contented. She was happier wanting than having.