The American-English phrase to have got sand in one’s shoes, and variants, mean to have come to enjoy living in Florida.

This phrase refers to the sand-beaches of Florida—as explained for example by H. H. Windsor, Jr., President, Popular Mechanics, in Sand In My Shoes, published in The Palm Beach Post-Times (West Palm Beach, Florida) of Sunday 17^th November 1940:

I’ve got sand in my shoes. It’s a different kind of sand—it’s magic sand—it’s Florida sand. It has been there since 1912 and each year it comes to life in the fall and starts its work. It’s like a lodestone that draws with magnetic power. It reminds me of the sparkling blue waters of the Gulf Stream; of the balmy days and nights; of the tropical moon and the wind in the cocoanut palms; of the friendly people who go out of their way to make one feel at home and enjoy to the fullest, the beauties and attractions of a great State.
[…] In my imagination I have felt the surge of the surf, whose mild temperature is ever constant and makes swimming in Florida a delight. Such is its power.
I’ve got sand in my shoes when I was a boy and it has been there ever since. How glad I am! I hope it never leaves!

The earliest occurrences of the phrase that I have found are from newspapers published in Pensacola, Florida:

1-: From the Pensacola Commercial of Saturday 12^th July 1884:

Mr. A. Dolhonde returned to Mobile last night, where he goes to enter into the coal business, having given the newspaper business the shake. It will be a cold day though when he gives Pensacola the shake; he has “got the sand in his shoes and is bound to come back.” We wish you good luck, old boy, in all your undertakings.

2-: From The Daily News of Friday 27^th July 1894:

Warrington.
Interesting Notes of Happenings in This Pleasant Town By the Sea.

Warrington, Fla., July 26.—The health of our town is exceedingly good. The only blue looking ones are the doctors who have nothing to do but wait and watch for a call, which seldom comes now.
[…]
Visitors from a distance are to be seen here every day taking in the sights.
[…]
Mrs. R. E. Morrill and her sister, Miss Lula Tanner, left yesterday for their home in Montgomery, having spent a jolly good time here with their kinfolks, Mr. John Morrill’s family, in boat riding and enjoying the splendid salt water bathing. Live [sic] every one who comes here they got “sand in their shoes” and are delighted with the place, so much that they are sure to come again.

The phrase then occurs in the presentation of “some of the veterans and their friends who have come to Montgomery for reunion”, published in The Montgomery Adviser (Montgomery, Alabama) of Thursday 13^th November 1902:

Capt. J. T. Stubbs of DeFuniak Springs, Fla., is one of the registered veterans. He was a Captain in the 1^st Alabama during the sixties. Captain Stubbs formerly lived in the Lowndes County. “But I got Florida sand in my shoes,” says Captain Stubbs, “and you know its [sic] mighty hard to get it out.”