Someone recently asked this question on LinkedIn on one of Adam Grant's posts on burnout.
The first thing is to recognize that YOU are the founder. You. NO ONE, and I repeat, NO ONE, will ever be as invested in your business as you will be. You might eat, sleep, repeat your business all the time, but that's because it's your baby; it would be foolish to expect your employees to serve as foster parents to Your Baby.
Avoiding burnout begins with founders setting healthy boundaries - not expecting people to respond to emails or calls at weird hours; taking time off for themselves and doing things outside of work and; actively spending time with people they don't know at work. I used to work with a colleague who overworked his butt off to avoid being lonely. No amount of interventions of any kind would help. Guess how high the attrition rate in his team was?
Setting boundaries around work for both leadership and employees always helps. There will be times when work is more intense for everyone, but this needs to be offset with downtime for everyone as well. And people need to know they don't need to be checking or responding to emails when they've just settled down to take a nap during downtime.
The second stupidly simple thing is - ASK YOUR EMPLOYEES. Just ask them what they want and they will tell you - but do it properly. A variety of surveys and interview styles can get this done in ways that bring you answers without employees feeling threatened or cornered into giving the "right answers".
Why do this? Because a number of organisations have seen high attrition, especially in high-stress industries because they don't pay heed to their employees' needs.
Most employees' needs often centre around personal growth and autonomy. Recognize and honour that and you can create a phenomenal culture around respecting individuals - where respect is mutual rather than subjective.