He'll go downhill so fast that a ship's anchor wouldn't hold him.
I think the hardest thing to do is to go downhill gracefully.
I have always believed that it is easier to go downhill than to go up.
And, ma'am, I know that his brother will be the ruin of John; he'll go downhill fast, as many a fine young fellow has done.
And then he explained to me that any fool can go uphill, ...