Mr Kettell said the box was uncomfortable as he made it too small
A 45-year-old charity fund-raiser has started a "wacky challenge" to be suspended in a box 25ft (7.62m) above Coventry city centre for a week.
Stuart Kettell, from Coventry, entered the box in Broadgate with only a blanket, a portable toilet and a bucket to lower down for food and drink.
The event for Macmillan Cancer Support began at 1700 GMT on Sunday.
Mr Kettell said: "It was very cold last night and I am just about getting the feeling back in my hands."
"I made it [the box] a bit too small and it's blowing about in the breeze," he added.
The box has a steel floor and measures 6ft (1.83m) by 4ft (1.22m), which he hopes will be his home until 1800 BST on Sunday.
"The reason I am coming back an hour later is because the clocks go forward and I don't want anyone saying I didn't do a full week," he said.
Mr Kettell said he was a "bit worried" about how people would react to him coming out of the pubs late at night, but has found most people very supportive so far.
He has raised more than £20,000 for Macmillan Cancer Support completing three "madcap" challenges since 2007, that included cycling 1,000 miles from Land's End to John O'Groats on a penny farthing bicycle.