Well, healthy lifestyle can cover many areas. If you spend lots of time indoors like I do (all the time) you may want to
1. try social activities
2. socialise with friends
3. participate in a game night
These kind of activities increase our dopamin levels thus making us happier and more productive. Well they actually work for me

When it comes to healthy eating my favourite ones are:
1. drink lots of water
2. eat more fish
3. balanced diet with controlled portions and of course
4. regular exercise.

Here is a very good list I got myself familiar with where you can also see quite a few healthy lifestyle tips https://brain-sharp.com/blogs/news/healthy-lifestyle-tips.

Let me know if these help in any way?