OP, You're human. The 'caveman' part of your brain, like everyone else's, wants pleasure over pain and ease over effort. That's why it tells you "you only live once, go for it" (Oh, not helped by the fact that lots of food is full of stuff that only ignites a sense of over desire.)
But the reasoning part of the brain, the bit that does the planning, knows this is a bad idea which is why you then feel guilty straight away - because you had a plan and you gave in.
But the great thing is that you recognise that. In your latest post you say you don't need to eat but you "choose to". Many others would say they didn't need to eat but did anyway and they don't know why. You are aware it's a conscious decision. That's very positive and bodes very well.
So here's another trick. Next time in that situation why not pause first then say (out loud if need be): "I choose NOT to eat this bagel/doughnut/whatever" Don't try to simply push the temptation to eat away; you don't want to do this via willpower (just that word alone stresses lots of people out!!). Instead concentrate on your thought that you choose to not eat it. Lean into this thought. How does it make you feel? Determined? Strong? Courageous? Yes, yes, yes. Not a drop of nasty guilt in sight. Do this enough and you train your brain that this is how it's going to be from now on.
If you can start to introduce this into your life, you will start to see changes. And if you do give in on occasion, don't give up. Next time simply concentrate on the thought that you choose not to eat the food in question.
This stuff really does work. I've helped loads of people with it.
And bravo on the DVD and dumbbells. You are taking positive actions in the right direction - you just need to get that brain into shape so it knows you mean business!