Certainly, the Church is all in favor of maintaining one’s health. However, obsessing on any one aspect of ourselves is to neglect to a degree the rest of ourselves. People do this by obsessing with work, or status, or control, or eating or not eating, etc. It’s a matter of imbalance. Bodybuilding is not a vocation. We exist for more than that. Your concern that it feels selfish indicates that you are aware that something is off kilter. To give such attention to one’s body is to make a kind of god out of it. Now if it were Christ’s body that you were giving such attention to, there would be no problem at all—because he is God. In fact, I suggest that you give some serious thought to how he has related to us through his body. It was sacrificial all the way. He has loved us with his body to the point of dying on the cross. I suggest that you eat well and keep a regimen of exercise to maintain your health. But the time you have used for bodybuilding, use for other things. I further suggest that you spend time reflecting on each of the sufferings he endured in his Passion and thank him—preferably before the tabernacle, but before a crucifix will do. I guarantee that this will not make you feel selfish. On the contrary, it will give your life balance and peace because this is your vocation. Every part of your life will fall into place.