KATHERINE Grainger is back in a boat and has a second Olympic gold medal in her sights.

The 38-year-old returned to training at Dorney Lake on Monday and admits the Rio Games in 2016 are certainly the end goal.

However, while a second gold medal is the ultimate ambition, Britain’s most successful ever rower insists that it is not getting ahead of herself after more than two years away from the sport.

She said: “I've agonised over this decision for a very long time. There was no one moment of 'eureka'.

“Some days, I would be driving and suddenly I would think, ‘that's me done, I'm never going to do rowing again. I'm ready for retirement. I'm prepared to walk away.’ “Then 48 hours later, I'd be doing something else and suddenly think 'I want to go back, I can't imagine why I wouldn't.”

After silver medals in three successive Olympic Games, Grainger finally broke through to win gold in London 2012 when she and double sculls partner Anna Watkins destroyed the field at Dorney Lake.

However, Watkins has already ruled herself out of Rio after becoming a mother and if Grainger does come get that far in her return she will have to find a new doubles partner or opt for the singles or quads.

She said: “If Anna was back in a boat, it would have been an easy decision to make.

“But I had to come back here and see how it feels. It’s very good sitting at home and making lists, but you have to see how it actually feels to sit in a boat, be in the gym and the changing room.

“I’ve missed the people and the environment and the training regime. At the moment it’s still novel but I know I’ve got to grind my way back up a very steep mountain and of course I think, am I absolutely insane?

“All the rational arguments say don’t come back, yet here I am.”

Grainger completed her first 90 minute session on Monday and will have a clearer idea of her progress at the winter trials in Boston on November 15 and 16.

She said: “I’m not making any promises to anyone. If it all goes well then the end goal would be the Olympics. But I just need to take one day at a time, one week at a time, one month at a time. Then I’ll start thinking longer term.

“I'm not really making long-term plans. A lot has to go well and fall into place. I have to get my fitness and my boat feel back and make sure I'm mentally where I want to be.

“The end point would be going all the way through to Rio, but I'm not making a commitment to that one just yet.

“There are going to be big challenges ahead in coming back after two years away. But if I don't try, I'll always wonder 'what if?' and for me, that will be so much harder to live with.”

Apart from her Olympic success story, Grainger was a world champion in 2003, 2005, 2006, 2007, 2010 and 2010, and won the GB trials in 1998, 2001 and from 2004 to 2010.