Removing/fixing indentations to leather seat?

My wife just bought a Honda with leather seats, it's in great condition but it looks like the woman who owned it before may have had a car seat strapped in to the rear middle of the seat. There are 4 indents (not tears, just depressions) in the seat that I'd like to try to remove, or at least make look a little better. I read a few methods online, one using hot water, a cotton rag, and a tennis ball seems like the least dangerous way but I wanted to find out if there was a favorite way of fixing this. Ideas appreciated!