Leonard Nimoy, who played Mr. Spock in "Star Trek," is battling chronic lung disease stemming from his longtime smoking habit, he announced on Twitter Feb. 6., 2014.
Nimoy, who quit smoking 30 years ago, urged fans to stop smoking now, saying the damage they're causing to their health has long-term consequences.
"Smokers, please understand," Nimoy tweeted. "If you quit after you're diagnosed with lung damage, it's too late. Grandpa says learn my lesson. Quit now."
Nimoy, 82, was diagnosed with chronic obstructive pulmonary disease (COPD) despite having quit smoking three decades ago.
COPD most frequently occurs among smokers. Symptoms include coughing, wheezing, shortness of breath and chest tightness. According to the National Institutes of Health, COPD is the third-leading cause of death in the United States.
In January 2014, Nimoy alarmed fans after being photographed at New York's Kennedy Airport in a wheelchair with an oxygen tube in his nose.
Nimoy, best known for playing Mr. Spock on the original Star Trek TV series, said he's doing well now but is unable to walk long distances.
"I'm doing OK," he tweeted. "Just can't walk distances. Love my life, family, friends and followers. LLAP [Long Live and Prosper]."