Multi-world and Olympic champion Usain Bolt said he kept working hard because he has been motivated by two main goals, one of them being winning Olympic title for the third time.

Talking to reporters on Friday ahead of the Diamond League competition in New York, Bolt said training was hard, but his hope to win a third Olympics has been his motivation.

"I have two main goals. One is to get on 19 seconds, I really want to jump on 19 seconds. And winning the Olympics three times. That's what keeps me going," said the Jamaican who will turn 29 on August 21, one day before the kick off of the Beijing world athletics championships.

Usain Bolt will compete in New York City for the first time since he set his first world record in winning the 100 meters in 9.72 seconds at the Icahn Stadium on May 31, 2008.

Since then, the Jamaican has won six Olympic gold medals and eight World Championships titles, and broken seven more world records.

The world's fastest man will run the men's 200m on Saturday although he hasn't been faster than 20 seconds 200m this year, with his fastest time being 20.13 achieved in Ostrava. But the world record holder was full of confidence ahead of the race.

"I'm not where I want to be yet, but I'm feeling better every day in training and I know what I need to work on," said Bolt, who held the world records of 19.19 in 200m and 9.58 in 100m. "I have to get more races under my belt, and just work on my execution."

Bolt said he is finding his best shape and will be ready for the Beijing world championships.

"I have 11-12 weeks until the World Championships. My focus is there, so I'll be ready to go when I am in Beijing," he said.

The 2016 Rio Games will be Bolt's last Olympics and Bolt all geared up for it.

"I already told my coach that I wanted to break the 200m world record next season, so I'll be racing over that distance a lot," he said. "The closer the Olympics are, the more excited I get. There will be a lot of sacrifices made next season and a lot of hard work put in."