Work, parenting, sports, coaching, relationships no matter the area leading by example is a worthy pursuit to help you and the others around you improve and grow.
If you want your kids to eat their vegetables, start by you eating said vegetables. You want everyone to use the proper header on the TPS reports, make sure your reports always have that header. You want your significant other to save more money, start by saving yourself.
Leading by example builds trust and buy in. If, as a gym owner, I didn't take our own classes how could I ask others to take those classes? The answer is I could not with a good conscious. I believe in our program, our community, and our coaches so I participate in all of it.
You are always leading by example but it might not be in a positive way. No matter what you are doing make sure you are doing it with integrity and you would be proud of it.