Exercise, even simple stuff that doesn't require going to a gym or expensive equipment like pushups and squats. I started doing those every day since the start

Exercise, even simple stuff that doesn't require going to a gym or expensive equipment like pushups and squats. I started doing those every day since the start of this year and I can't believe how much it has improved my fitness and health. Squats in particular gave me a lot more stamina with running, climbing stairs, etc. It takes less than 10 minutes a day to do a few of each (I worked up to doing 50 of each) too.