Jethro Tull founder, visionary and multi-instrumentalist Ian Anderson has revealed that he has been battling chronic obstructive pulmonary disease, what he described as an "incurable lung disease," for the last "couple of years."

The revelation came in a newly-released clip from the upcoming May 13 episode of The Big Interview with Dan Rather, which features the prog rock legend.

When Rather asked Anderson how he manages the stamina needed to perform onstage while also singing and playing the flute, Anderson replied, "I’m going to tell you something I’ve never told anybody in public before – I am suffering from an incurable lung disease which I was diagnosed with a couple of years back."

Admitting it is a "struggle" to deal with the disease, Anderson also explained he suffers from "exacerbations," which the 72-year-old musician described as "periods when I get an infection that turns into severe bronchitis and I have maybe two or three weeks when it’s really a tough job to go out there on stage and play."

Fortunately, the rocker has been exacerbation-free for the last 18 months and that he's currently taking medicine to augment the struggle. "If I’m kept in a reasonably pollution-free environment in terms of air quality, I do okay," he went on.

The future, however is bleak as Anderson confessed, "But my days are numbered." The Jethro Tull icon next suggested his standard routine hasn't been impacted too much, when he commented, "It’s not yet at the point that it affects my day to day life – I can still run for the bus,"

When Rather pressed Anderson about the prognosis, Anderson is taking it by the day. "Fight it all the way – keep using as much of your lung power as you’re lucky enough to have and push it to the limit all the time," he said with confidence, and cautioned, "The minute you settle back and say, 'I can’t do this any more,' it’s a slippery slope. The answer is keep pushing."

Touching on the disease, Anderson explained, "Popularly termed COPD, where you lose some of the ability of your lungs to give you enough oxygen." He then attributed the condition to time spent onstage over the last half century breathing in the plume of fog generated by smoke machines.

"Today, they’re politely referred to as hazers, as if they’re somehow innocent and not damaging to your lungs," the rocker scorned, concluding, "I really do believe that’s a very significant part of the problem I have."

Watch the interview clip below and look for Anderson's full appearance on The Big Interview with Dan Rather on AXS at 8PM ET tomorrow (May 13).

Anderson has remained an active performer, electing to tour as a solo artist rather than under the Jethro Tull moniker over the last decade. The rocker celebrated 50 years of the band's legacy in 2018 by performing Tull originals on tour, and hit the stage as recently as Feb. 29 in Madrid, Spain.

Jethro Tull's Ian Anderson Reveals 'Incurable Lung Disease' on The Big Interview With Dan Rather