Lighter boots

In Extremely Loud & Incredibly Close by Jonathan Safran Foer (Everything Is Illuminated), the 9-year old narrator-protagonist Oskar uses the phrase "heavy boots" to describe feelings of depression/nervousness/sadness.

Some things that gave me lighter boots this past week:
Gorgeous sunshiney weather
Kellogs' Crunchy Nut cereal with strawberries and bananas in milk, every morning (=
Molding rabbits out of plasticine
Plans for picnicking-cum-studying sessions in Hyde Park during Easter hols
My "Poem for the Day" book from Sook Meng
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The average person falls asleep in seven minutes, but I couldn’t sleep, not after hours, and it made my boots lighter to be around his things, and to touch stuff that he had touched, and to make the hangers hang a little straighter, even though I knew it didn’t matter.
- Jonathan Safran Foer