[excellency]

Hey everyone,
I have a question about infinitives. There is a structure that says: an infinitive can be used as a noun, an adjective, or an adverb. I know about an infinitive that is used as a noun but my problem is with adjective and adverb.
For example:” to train is hard work.” Here to train is the subject and a noun.
But what about these ones? I have two examples for the adjective and the adverb.
She always has energy to spend. To spend is as an adjective.
He ran to win. To win is as an adverb.
Can anyone help me with these two examples? They are so strange to me. I have no understanding of them. Can you give me your own examples?