I think you'd have to be very careful not to alienate people by assuming you know better than them how to handle the daily struggles their lives throw at them.
What could be seen as expertise could also be seen as a failure to really understand people, their motivations and priorities, and could certainly come across negatively.
I have a very complex medical condition which many medics with no relevant experience believe wrongly, can be controlled easily by facile and glib solutions. They fail to understand either the condition appropriately, or that I am an expert at managing my own condition. I've learnt to nod and smile at those people, as they are far too arrogant and entrenched to bother to engage with.
The best people have both been experts at the condition, and respectful of a patients own knowledge and experience. Rather than vaguely remembering something from medical school which has since been overtaken by new research, or believing 'they can do better'.
Most of all, real experts are people who don't assume they know better than the patient from a tiny snapshot of their condition, history or daily lives.
I'd hope you wouldn't be falling into the same trap. Im sure there are real lifestyle and behaviourial changes in these more mainstream conditions. But i do wonder why you think these people dont know what they should be doing, and why you think just telling them to do things differently would have any positive effect... Or reach the people that need it.
It does sound like your perspective is based on a tiny sliver of knowledge - filling peoples prescriptions, without knowing patient medical history, lifestyle, doctors / gp diagnosis or what contact patients have with other sources of management, support or expertise.
If I were you, I'd start by filling in my very limited perspective and then determining whether there is an unfulfilled need for your help, and that you are best placed to engage with the right audience, in the right way to effect a meaningful and genuine change.
I would not start with rushing in telling people where they are going wrong.
HTH.