An Immortal

"So I'm an immortal," asked Jason Lambert.
"Yes, you are," responded the doctor.
"I won't die if I get hit by a bullet."
"No."
"How about a nuclear explosion?"
"Your body can withstand a nuclear explosion."
"Amazing. So I won't grow old?"
"Not at all. You'll look forty all your life."
"Wonderful. Thank you so much."
"There's just one problem."
"What is that?"
"I'm very sorry but we could not solve this particular biological problem."
"Which problem is that?"
"You have unfortunately become impotent. I am really sorry."
"Impotent, but you told me that no changes would be made to my current biological functions."
"Changes were made so you could be immortal. Do you accept the changes or do you wish to revert back to your former self."

Jason knew that he could not go back.

"I accept."