Nutri-grain, to anyone over the age of about 14, is basically sickening stuff. They did well with their marketing adage though, 'You only get out what you put in.' Rather than than a mix of pulverised cereal and refined sugar however, let's talk about effort and attitude in training.
Skills and fitness are easy to get. We all have potential and we can reach it by training enough in the right ways. Easy. Done. Why say more? Because training in the right ways is difficult, and in a team sport we need everyone around us to put in as much effort as we do. Skills and fitness are easy to get, effort is not.
Training is really important, not because of the beers you have afterward, but because you play the way you train. If you don't lay out in training, how will you lay out in a game? if you taper off as your opponent scores in front of you because it's only training, how wil lyou stick with them in a game? Your muscles remember what to do, and recall it quicker than your brain does. To be the best player you can be, you need to give your muscles the right memories, and those are ones of maximal effort when it counts.
Training as a team in a team sport allows for cohesion to form, and training with effort helps that. Not only does a layout pump you up, it pumps up everyone on your team. If that happens in training, it transfers to games. So next time you go out to train, remember to put in maximal effort. Your team deserves nothing less from you.