Hi Marc
I've radically changed my whole life over the past 5 yrs and I've done it by taking small baby steps all the way. You can't successfully work on each area so choose one area that you want to tackle first. Then break it down into tiny goals.
The other thing is you say about your poor diet. You might like to read an article I wrote a while back about how poor diet leads to exhaustion
Poor eating
Alison