I have been sober for more than forty years. I have been an environmentalist for longer than that. I have Parkinson's disease. I am, by most measures, a very lucky man.

The connection between those facts is not accidental. Sobriety gave me the clarity to see the world as it actually is. Environmentalism gave me a mission that outlasted any role, any award, any moment of recognition. And Parkinson's — which arrived uninvited in my sixties — has given me something I didn't expect: perspective.

When people ask me how I cope with the diagnosis, I tell them the truth: I cope the same way I've coped with everything since 1979. I try to do the next right thing. I try to leave things better than I found them. I try to remember that the planet does not care about my tremor, and that the work does not stop because I am inconvenienced.

The temple of tranquility is not a place. It is a practice. You build it one decision at a time.

I live in Studio City, California, in a house that generates more electricity than it uses. I drive an electric vehicle. I have been riding an electric bicycle since before most people knew what one was. None of this makes me a saint. It makes me a person who does the math.

The math on climate change is not complicated. It is just uncomfortable. The math on sobriety is not complicated either. The math on Parkinson's is somewhat more complicated, and I will be honest — I am still working it out.

I am grateful to Saturday Review for the invitation to write in these pages. My father read this magazine. I grew up knowing it mattered. It still does—maybe more than ever.

Ed Begley Jr. is an actor, environmental activist, and author of To the Temple of Tranquility.