It is probably the single biggest & best thing anyone can ever do for themself.
One very good place to start is getting a greater understanding.
Many things come to mind as suggestions - but here I'll just share my top 3:

1.
A documentary movie called 'Food, Inc.' (Netflix has this...) reveals things which can be quite surprising.

2.
Another (shorter) documentary called 'Processed People' which is harder to find, but should play if you visit this site where I viewed it:
http://vidreel.com/video/NTkwMjA2/
(Here is the source site in case that one doesn't work-> http://freeviewdocumentaries.com/201...cessed-people/ )

3.
Sugar: The Bitter Truth
By:
Robert H. Lustig, MD
http://www.youtube.com/watch?v=dBnniua6-oM

I suggest the above as starting points for most folks just because in our so-called 'modern world' there is actually a desperate need for folks to simply get better clues as to what they are swallowing regularly that they don't even know about.