I believe that part of being successful is eating healthy and exercising regularly.
I'm not saying you can't be successful without adopting these habits - au contraire - but it certainly places you in the right frame of mind.
Eating healthy takes discipline, determination, and the ability to say "no" when a decadent dessert is right in front of your nose. Exercising regularly provides you with a routine to follow, and often allows you to realise that you can push past your limits.
Having been an extremely unhealthy and quite overweight individual a few years ago, I certainly believe this. It hasn't always been easy to uphold, as the urge to indulge can be too much sometimes.
I don't believe in diets - I believe in eating everything in moderation. I think if you cut out one player in the food pyramid, then you're opening yourself up for intense cravings. I tried slow-carbing earlier in the year, and became thoroughly sick of it in a week. As a girl who loves bread, the week of denying it made me crave it for a month. And I hated the idea of a complete binge day.
Right now I'm recovering from a hip sprain injury. When I was exercising I tweaked the muscle a bit, and didn't listen to my body to slow down. I've had to take it easy the past few days, but it has really allowed me to focus on my diet. I'm trying to drink more water, pay closer attention to my stomach when it's signaling me it's full, and shush the voice that wants instant gratification.
How does this all tie into success? I certainly don't have a chart or any experiments conducted on mice to demonstrate a correlation, but I know there's a feeling of wellness within when you eat healthy and exercise. That sense of lethargy is gone, and you can say: (for example) if I managed to exercise for 'X' minutes, I can do 'Y' task. You can attribute your success of living healthy to other areas of your life, and allowing the generated success to snowball.
So maybe next time you are at the grocery store grab the raspberries instead of the chips, and when there's a commercial break in your favourite show, do 10 pushups! There's a little bit of success in itself already!