What's a life lesson you learned the hard way that you'd want to share with others to help them avoid the same mistake?

You know something that helped me exercise regularly was.. "you're going to be scrolling through your phone. Might as well do it while on the treadmill/peloton/etc"

Don't try to have a good diet and workout routine, try to regularly improve your diet and workout routine.

The best workout routine is the one you can stick to. Plenty of people online will tell you that to lose weight you need to be doing cardio in a certain heart rate zone or to gain muscle you need to weight lift a certain way. That is technically true, but useless. A great workout routine is just walking for half an hour each day. It is a much more realistic goal for out of shape people and simply getting your heat pumping and your muscles moving regularly will get you most of the health benefits you need.

Same thing with diet. A keto or intermittent fasting diet may be the fastest way to burn fat, but they are very hard to stick to and when you break them, you will be so hungry that you will eat enough to gain back all the weight you lost. A more realistic plan is to cut out a sugary beverage from each day and to make sure that every meal includes a vegetable high in fiber. Once that is an established habit, build on it with other small changes that move you closer to a healthy lifestyle.

I heard the same advice about investing for retirement. This feels like a glitch in the matrix.

I work a very sedentary career and don't have a ton of energy after work/kids, but I've found having an under the desk pedal cycle to use during the day has done wonders for my physical and mental health.

But don't switch completely to a healthy diet all of a sudden, do it slowly. Otherwise your body may not handle the drastic change and you may get health issues (mine was a belly button infection 🙃).