The single most important thing in your control on a daily basis to decrease all cause mortality risk and increase your longevity is to simply hit 8k+ steps per day - this may seem a little daunting especially as a busier person, but taking a 10-15 minute walk after your meals is an incredible way to stack these steps, improve digestion, insulin sensitivity, decrease blood pressure and a host of other benefits.
IN ADDITION: if your goal is to get into a calorie deficit and lose fat, hitting a consistent amount of steps increases your NEAT (non exercise activity thermogenesis) aka all the calories you burn that isn't directly cardio or high intensity exercise. You can't just pull your calories down forever, it def helps to increase your activity as well so you aren't starving yourself.
Walking is SUPER MF underrated! Most people just aren't nailing the basics consistently, let's not overcomplicate the hell outta this!