--- Don't get too busy ---
If I was to do it all again, I would learn the word "no".
At times I was training everyone and everything, crazy.. I see it all the time with coaches.. Going to a wedding or booking a holiday is a chore, relationships suffer and so does your waistline.
I personally got into this game to be as fit as I could, now I always struggle with being fit, but still, I loved the challenge - 5 years of drinking coffee and driving up the N4 will kill anyones spirit. I stopped training and was codding myself that my clients only matter.
Say NO to anything that's a pain in the head. Long commutes, house visits, moaning customers, discount seekers etc.
Never work weekends - you may get Monday off but the rest of the world doesn't. Enjoy your weekends!
Take two holidays a year. Visit the world, there's more to life than chin ups and clean and jerks.
Get a great team around you, Do you really need yourself to hold that stop watch or fill those protein bottles all the time? I'm lucky as I have GREAT people all around me.
Train minimum 4 days a week.
I could write more but it's a nice day and I'm off for a coffee in the sun.