Singer Sonu Nigam is spreading cheers across the US with his Klose to my Heart tour, and says it has been his toughest schedule ever.

He is in the midst of his 15-city tour of the US and Canada, which began June 1. He has been loving the experience.

"This tour has been the toughest ever in terms of effort. To the extent that I need to take a break now. Exhausted. But the thrill is addictive, " tweeted Sonu whose tour ends Saturday.

He also suffered chest infection last week.

"Crazy travel schedule coupled with chest infection last week made life difficult. Concerts were blessed though."

"Winnipeg, Edmonton and LA were memories to cherish. Glad it all went that well. Just landed JFK (John F. Kennedy International Airport), off to Connecticut. Four concerts this week, " he added.