Employee Performance - Help Needed

I agree with colleagues and sympathize with the challenge you face in delivering on this project.
At the risk of being somewhat controversial, I am going to offer you a starting point / answer to your "what percentage" question. My starting point would be 2%
How did i land there ? Approx 240 working days in a year ( excluding 20 days annual holiday) and a "budget" of 5 days / 240 per employee for development and training activities would not be untypical of some of the companies in which I have worked in the past. Now that leaves you with well-being, engagement and work-life balance and as colleagues have said... very much a matter of definitions . If "well being" was defined as participating in one half day workshop per year on healthy diet and exercise and being allowed to leave early ( one hour per week) to attend a gym that would be another 2.7%
If engagement was narrowly defined as 2 days per year engaging in a community activity that's another 0.8% If work-life balance was defined as making use of a flexible benefits/holidays scheme with a facility ( through salary sacrifice) to purchase 5 extra days holiday per year that's another 2%. In conclusion with the above completely random definitions and assumptions I am up to 7.5%
The main purpose of my response is to give you some examples to use as a way of engaging with your boss and seeking clarification on exactly what she wants. I'm guessing that few of the above assumptions are likely to be on target but establishing what the project is NOT about may help you get a bit closer to what it IS about.

I agree with colleagues and sympathize with the challenge you face in delivering on this project.
At the risk of being somewhat controversial, I am going to offer you a starting point / answer to your "what percentage" question. My starting point would be 2%
How did i land there ? Approx 240 working days in a year ( excluding 20 days annual holiday) and a "budget" of 5 days / 240 per employee for development and training activities would not be untypical of some of the companies in which I have worked in the past. Now that leaves you with well-being, engagement and work-life balance and as colleagues have said... very much a matter of definitions . If "well being" was defined as participating in one half day workshop per year on healthy diet and exercise and being allowed to leave early ( one hour per week) to attend a gym that would be another 2.7%
If engagement was narrowly defined as 2 days per year engaging in a community activity that's another 0.8% If work-life balance was defined as making use of a flexible benefits/holidays scheme with a facility ( through salary sacrifice) to purchase 5 extra days holiday per year that's another 2%. In conclusion with the above completely random definitions and assumptions I am up to 7.5%
The main purpose of my response is to give you some examples to use as a way of engaging with your boss and seeking clarification on exactly what she wants. I'm guessing that few of the above assumptions are likely to be on target but establishing what the project is NOT about may help you get a bit closer to what it IS about.