After wrapping up his extensive "Forget Tomorrow" world tour, former NSYNC star Justin Timberlake got candid about his health struggles - namely, his recent diagnosis with Lyme disease. What is Lyme disease?

Chris Kirkpatrick took to Instagram to shower praise on Timberlake, who revealed Thursday that he was diagnosed with the debilitating disease.

LOS ANGELES — Justin Timberlake has been diagnosed with Lyme disease, the former NSYNC star said on Instagram Thursday. Timberlake shared the news in a post commemorating his Forget Tomorrow tour, which wrapped in Turkey on Wednesday, adding that the disease “can be relentlessly debilitating, both mentally and physically.”