I'm 15 months into my RP journey. I had a few setbacks along the way. One thing I found was that when things went badly I got back on track by lifting, reading and sleeping, mostly in that order. After a while it becomes second nature, but while you are learning it is important to know to just fall back on these things every time you get discouraged. Do the work. The transition will take care of itself.
The RP process is emotionally draining. Lifting is physically tiring. Dieting is draining. Having a bad day ? Check how much sleep you are getting. Cut out the TV and get a good nights sleep. Go to bed at 9:30. Rest. Worst case is you'll wake up at 5:30AM rested and then you can easily take care of shit.
Can't sleep at night ? Work out harder. Eat a high fat, low carb diet. Cut out caffeine. Learn to meditate.
I keep an Android tablet beside my bed. If something is bothering me I open the tablet and journal about it until it is captured and then worry about it in the morning. I cannot sleep if something is bothering me and I want to remember it to work on it in the morning. I need to capture it, then and there and then sleep.
Just do it. Sidebar books, other books and the RP Reddit subs. Whenever you get off track, start reading. Screw up a shit test ? Read. Get butt hurt ? Read. Argue ? Read. DEER ? Read.
If you are BP, you've been screwing up shit tests, getting butt hurt, arguing and DEERing for the last 20 years. Those behaviours are burnt into your subconscious. You do them automatically. You don't change them by reading a bit. You have to work on the how, why, when of those behaviours over and over before they become second nature. "You are such an ass !" "Yep, I am really good at it !" "I'll be even better next week" Or STFU...
I like to read old RP Reddit posts when I'm down. My problems don't seem so bad when I read about everyone else's. And usually I glean a nugget or two from a thread.
Anger is a normal by product of realizing you've been screwing up your life for the last 20 years. The best way to deal with anger is to work out until you are exhausted. For me that turns the anger into something softer, like sadness, guilt or remorse. When I feel those emotions, I get some sleep. In the morning I feel better. I'm ready to start another day.
Work outs produce a variety of feel good chemicals like endorphins. It is rare that I don't feel better after a work out. Remember that you control your state of mind and work outs are one way to do that. You don't have to be fat. You don't have to feel shitty. You control how you look and how you feel.