"Choose a job you love, and you will never have to work a day in your life," as they say. For cannabis lovers, there's probably never been a better time to combine business with pleasure.

Countless celebrities are also looking to carve a niche in the legal cannabis industry: just ask Willie Nelson, Ross Rebagliati, Roseanne Barr, Melissa Etheridge, Snoop Dogg, or, pretty soon, Whoopi Goldberg. But in an increasingly competitive market, even name-recognition doesn't guarantee a hassle-free segue into the industry - as proven by these three three celebrity case studies.

1. Woody Harrelson

According to Reuters, Hawaii lawmakers recently turned down the application of Harrelson - the former "Cheers" star who has also played lead roles in the Hunger Games series and "No Country For Old Men" - to open a medical marijuana dispensary on the island. But Harrelson is hardly alone: of the 60 applications the state received, only three in Honolulu, and five more on Big Island, Maui and Kauai, were approved. (Tetris co-founder Henk Rogers and TV producer Dirk Fukushima also applied to open dispensaries, and were turned down.) It's unlikely this will be the last we hear about Harrelson attempting to forge inroads into legal cannabis: a long-term marijuana activist, he founded Simple Organic Living in 2015, and sits on the board of NORML.

2. Nick Lachey

Erstwhile boy band and reality-TV star NIck Lachey became a Responsible Ohio spokesperson after announcing a plan to open a 29-acre cannabis farm outside of Akron, Ohio. Too bad those plans were scuppered when Ohio voted against legalizing marijuana last year. Lachey was disappointment, but took the setback in stride:

Despite the let-down, it's probably fine that the plans fell through: it looks like 98 Degrees is touring again this year with a cohort of other 90s-kid nostalgia acts like O-Town and Ryan Cabrera.

3. Wiz Khalifa

Shutterstock / Randy Miramontez

The Grammy-nominated rapper recently announced his partnership with RiverRock Cannabis to sell regulated concentrates, flower, and edibles that Wiz says have taken "years" to develop, but it hasn't been entirely smooth sailing.

Khalifa tells GQ, "It was never really a goal of mine to get into the business, it developed over the past two or three years and became much more serious. My goal was literally just to get a weed card. But then I started figuring out what you can do, and it just started making sense. That's when I started building my business around it. Now we're at a place where I feel we're going to be able to do something nobody's ever done before."

While the product line launched on 4/20 in Colorado, federal law still prohibits cannabis from legally crossing state borders. According to an article in The Cannabist, that Colorado pot shops distributing Khalifa's products couldn't get clones for the strains from Cookie Co. 415 that were grown in California. Instead, they had to meticulously recreate the strain in Colorado, "a particular phenotype of OG Kush."

h/t The Cannabist, GQ, The Huffington Post.