The heart
A river
He LOVE'S HIS FANS he'll never get tired of them!
A Path
The heart itself is a muscle that never gets tired. This is, in part, due to the inclusion of the cardiac muscle and the constant blood flow to the heart itself. Skeletal muscles tire after prolonged use and cardiac muscles maintain stamina for constant use.
stairs
tireless
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nothing
A poptropica person never gets a fever.
A person often gets tired when exercising, so they breathe harder than normal.
because person gets tired