One of the most interesting things I come across with people who are working hard to achieve a goal is still there ability to justify earning activities that do them no good.
A great example comes from people whose goal is to lose weight or improve body composition. They come to the gym and work their butt off and, because of that, think they've earned the right to eat crap. Jokingly, I've heard people look at the calories they burn in a workout and talk about earning the donuts they are about to go eat.
In one of my favorite leadership books, Wooden on Leadership: How to Create a Winning Organization, The great John Wooden wrote, "Following a grueling basketball practice aimed, in part, at building up players physical strength, I would advise them the following: 'All we've worked so hard in accomplishing on the court today can be torn down quickly, in a matter of minutes, if you make the wrong choices between now and today's practice.'"
Same goes for you. All the hard work you do in the gym becomes voided out if you don't make the right health and lifestyle choices between training sessions. Don't ever think what you do in the gym gives you the right to make the wrong choice. It should enhance the reason to make the right one.