He's smiling, the Olympian, the once-upon-a-time gold medallist, the used-to-be world champion, the 10m air rifle shooter who never wants you to look deep inside him, but inside him right now he's not really smiling. He's wincing. He's finished his fifth and final Olympics on Monday in what he calls "the worst place to be in".

Fourth.

He doesn't even know by how much. He doesn't care. How does it matter? By two points or by 0.1 it's still fourth place.

Ah, the Olympics, it doesn't break your heart, it stomps on it.

Abhinav Bindra is in the bowels of the Olympic Shooting Centre, on his way to a drug test, his career done, his gun jocularly offered to a journalist for a cheap price. A few corridors away in the main hall the victory ceremony is going on, but he's not invited. He's still fourth and it still sucks.

Fifth place would be fine, fifth isn't really in with a chance. But fourth is too close, it's "what if" land, it's "oh s***" country, it's a medal touched, it's history flirted with. His last shot of his competitive life is a 10, it's perfect you think, except in the shoot-off for bronze his rival with a 10.5 is more perfect.

People come and shake his hand, they say "sorry", they shrug.

Fourth! Damn!

"Of course it hurts." Bindra is smiling again and yet he's not.

On Monday morning I travelled across Rio to watch Bindra. He's an oxymoron, a famous shooter. From a land of over a billion people, which has been independent for 69 years, he is the only Indian to ever win an individual Olympic gold. He probably wishes there was another, just so that he didn't have to answer a question on it again. He's smart, funny, ironic, feisty and is also known to be boring. He's not a man to liven a party but if you want to know what happens when you take a "little talent" - his words - and oil it with obsession, he's your guy.

Journalists wander around the Olympics and watch athletes for various reasons: Because they're from our nations, they're gifted, they're controversial, they have hard-luck stories. But this morning is different, it's personal, it's emotional, it's about watching a young man I admire who is saying goodbye to the Games. I've helped with the writing of his book, A Shot at History, and yet I've never seen him shoot at any of his five Olympics. He is very thoughtful on this matter: all morning he has me at the edge of my seat.

How does an athlete - and there will be many in Rio - say farewell forever to the Olympics? To a sporting life, to obsession, to purpose, to dreams? To something they wake up for and go to sleep with every day for 20 years?

Bindra has been 2008 Olympic champion, 2006 world champion, winner of 10 medals at the Asian and Commonwealth Games, and he may not agree just yet but perhaps this is not entirely a bad way to end a grand career.

Forget the fourth place for a minute and think of it this way: he's finished his career with a day of raw competition; with a hard scrap to the end; with his gun-sight broken in the morning and not falling apart; with a fall to 7th place in the final and then a comeback to 2nd place; with rhythm coming and then going but perfection desperately pursued to the last.

It's a day when nothing is easy, a day that encapsulates the craziness of shooting, a day to slam the door shut on sport with. A medal would have been fairytale stuff but at least this wasn't a tame end, not an athlete past his best limping away, not a day of nothingness. This was endless struggle. And that's who he is.

All his life, since he first smelled gun oil as a boy, Bindra has been a shooter who was hostage to his own extraordinary obsessiveness. How far do you go to excavate your best shooting self? How far is far enough? One day in Durban he shoots eight straight hours till he runs out of pellets. That far?

Through the years he will meditate, sky-dive and run 8km with a heavy backpack. He has his brain mapped (sensors on his head to check how much chatter is going on inside), climbs rock walls blindfolded and shoots in pitch-black rooms to work on his awareness and balance. In time, and over conversations with him, I will find that the champion's mind is a brilliant and scary place.

Then one day the athlete says enough. We'll never know precisely why and he doesn't owe us answers for we never made him great. He packs his gun, his pellets, his career. He finishes his last shots, last questions, last rites. At 33, the thought of a new life will make him nervous but he started his old life - as a shooter - from scratch and seemed to do OK.

When I last see him he is walking away in that odd gait of the heavy-booted rifleman. Then he turns and says: "At least I have a gold medal."

And Abhinav Bindra starts to laugh.

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