nActually I think it is a good thing to work out even with PKU, if you increase your intake of formula, you will be able to roll with it pretty easily, and it will probably help you sleep as it would use that extra energy you have. I actually weightlift and I am doing great with it. I just treat the formula as I would a protien drink and slug it like its water.
If I were you, I wouldn't try to fit in with the crowd, granted you have PKU but you don't have to define yourself by it. You don't need disability to be successful. Think, you're the man, and you can make it happen anyway.
Oh trust me i have triedbut it seems as of late i have been getting worse over the years. Just recently i have trouble in big crowds and at work they wanted me to talk to customers and there were like 6 people around. I got so nervous and red that on the right side of my face it felt like it was buning up to the point where it was worse then a sunburn. trust me i would know. There are some thing i can and cannot do and being stressed out like that makes my condition worse.