What is "walking in high heels" in "I get tired walking in high heels"?

[Mori]

I get tired walking in high heels.

Source: Broadview Anthology of British Literature

I'm not sure I understand this structure: Can we say it's an adverb phrase?
I get tired when I walk in high heels. (Adverb clause)
I get tired walking in high heels. (adverb phrase)

Or is it the object of a preposition?
I get tired (from) walking in high heels.
Like I had considerable difficulty (in) persuading her to leave.

 

[Tarheel]

Do you understand the sentence? Does it make sense to you?

(In my humble opinion, your analysis is fine.)

 

[Mori]

Do you understand the sentence? Does it make sense to you?

Of course. I just don't understand the grammatical structure.