Is it worth exercising if I only have a few minutes a day?

Yes! This is so important especially because of how often I see people fall into all or nothing type of thinking with exercise. During school I did an in service (presentation of current research) on exercise and reduction of all cause mortality and the basic take away was a very small amount of exercise per week ends up making an enormous difference. In fact it can be incidental exercise like running up a flight or two of stairs every time you take a break at work on go upstairs at home. The benefit is cumulative and does not meaningfully change if you do the minutes of exercise in sequence or spread throughout the day. Something as simple as walking fast from the parking lot into the grocery store or work, going up stairs quickly, doing one set of squats in the morning or just chasing kids/grandkids around adds up a meaningful change in health. Something that you would consider vigorous exercise, whether done intentionally or added throughout your regular day makes a meaningful difference in health. Your starting point and context matters, but as little as 15-20 minutes a week can reduce all cause mortality by up to 40%. So if you are tempted to fall into an all or nothing mindset, just remember it is absolutely worth doing that 5 minute jog/walk/squats/ whatever else.