I live in San Diego, which weather-wise makes it easy to bicycle every day. San Diego also as a reasonable bike path system, though there are still lots of places where I dice it out with cars. I started biking because I was morbidly obese and in poor health. After getting my diet and regular cardio in order, I shed the weight and my goals began to shift towards adding muscle mass as a metabolic sink. I started hitting the gym regularly, and cut out the dedicated cardio, which was time consuming. However, I needed to keeps some cardio and I enjoy biking, so I set up an old '90s mountain bike with a rack and basket for carrying stuff and decided that I would bike as much as reasonably possible for transportation, which generally means that I'm biking everywhere that's within 30 minutes, and considering biking if it's going to be a 30-60 minute ride. As it stands, I bike about 5K miles per year, which is more than I drive. I average ~1hr per day on the bike, which isn't a ton, but it is something and burns ~750 calories.

If you're interested in doing something similar, '90s mountain bikes make great city bikes. They have gearing that can easily handle steep hills, they're super durable, as they were made to be hammered off road, and they're dirt cheap, as they were cranked out by the millions. I have a '95 Trek 820 that I paid $45 for that was in pristine condition. It even had the original tires with the nubs still on them. I've since gotten a '92 Trek 820 for free that had some nice upgrades, so I've been riding that lately. It doesn't take much to get started, but you need to have the bike set up to be useful, and having a rack with a milk crate zip tied to it as a basket allows you to just toss your groceries or whatever in the back, making it easy to live with.