Something that has helped me stay healthy and not neglect my health is having a 'fitness standard' to work towards.
In business we know that when we have clear targets we achieve superior results.
I believe we should do exactly the same with our health so we know what we're working towards and how to measure progress/success.
It's perfectly reasonable to achieve these standards at any age with about 30 minutes 4-5 times a week.
I hope it helps you like it's helped me.