I think you're at your limit and you can't take on one more thing.
It was at the limit of what he could see.
"I was doing right at my limit, trying to stay in the first 10," he would say later.
He was nearly at the very limit of his freedom.
"The white one there is just about at the lower limit for size."
The area was then at the limits of London's growth.
I had a full day yesterday and I'm about at my own limit.
At the limits of their vision, miles south, they saw people.
Yet his strength was at its limit; what more could he do?
Still fast at the limit, it now takes more work to get there.
