The Wall Street star, who is married to Welsh actress Catherine Zeta-Jones, wore a Cyrmu (Wales) baseball cap as he tended to his daily duty.
Douglas has been undergoing chemotherapy and radiotherapy treatment for throat cancer. He reportedly finished treatment earlier this month.
In a recent interview, the 65-year-old actor told reporters he was determined to win his cancer battle: “It’s a fight. The treatment is brutal. It really knocks you out. But I’m going to beat this.”
Michael has also been honest with them about the imprisonment of his 31-year-old son Cameron with his first wife Diandra Luker – who was handed a five-year jail sentence in April after pleading guilty to dealing methamphetamine and cocaine.
He said: “The children have been fantastically supportive. I’ve taken them to watch my radiation treatments so they understand what’s going on, and I’ve taken them to see their brother in federal prison. It’s brought us a little closer in some ways.”
Although Michael is positive he will win his cancer battle, he admits the treatment has taken a “big toll” on him.
He explained: “I’m finding that solitude and quiet is what I really need. I’m really enjoying listening to music and reading books, but the radiation and the increased soreness of my mouth and the chemo continue to knock me out. On the one hand, my tumour is shrinking and getting a lot smaller, but on the other, the processes used to eliminate it is taking a big toll.”