Amir Khan says that at 31, he is at the "peak of his career" as he prepares to fight Samuel Vargas next week in Birmingham.
The former world champion returns to the ring on September 8, live on Sky Sports, to take on the Colombian. He will box back at 147lbs for the first time in over two years.
Khan made his comeback with first-roundnd knockout of Phil Lo Greco in April, and believes he is in the best shape possible ahead of his next test.
"I still feel strong, I was running against the young 23-year-olds (in training camp), then sparring against 25-year-olds who are at the peak of their career - and I was out boxing them," said Khan.
"I was doing so well, so I was thinking to myself 'age is just a number for me'. I work harder than most young fighters.
"My work rate was a lot harder than theirs, and this was against young up-and-coming fighters who I believe will become world champions. I really feel young, explosive and strong."
There is just eight days to go until his bout with Vargas, but Khan is already looking beyond that fight and wants to prove he is world class.
"This next fight is very important to me, beating Vargas, not just beating him but also looking really good against him will only take me onto the big world title fights," Khan said.
"I'll be challenging for a world title in my opinion by the end of the year, or early next year."
He added: "It's how you look after your body. In training camp I worked hard, I never cheat myself. At 31, I'm at the peak of my career."
Watch Amir Khan v Samuel Vargas, from the Arena Birmingham, on September 8, live on Sky Sports Action from 7pm.