I was a geek at school. I have only deliberately faked illness once and that was on sports day- it was humiliating and the team sports made no sense and were overwhelming for me- I was put with the 'YRs' in year 6 to 'Help' them as I couldn't do the activities properly (and was terrified of falling off the bloody balancing equipment, thanks shit depth perception).
I also avoided it when I went to Sixthform - said I was on a uni open day (Tutor found me out and found it hilarious as I frantically tried to blurt out a 'cover' story and told me she would keep it hush as she did exactly the same as a kid so wasn't one to talk!).
Avoiding PE does not equate to challenge avoidence or even avoidence of exercise. I bet there are people that have sneaked off something in life and still are very successful people.
For the record, I have severe dyspraxia, SPD and mild cp. I have done my DofE award, 200 hours volunteering award, will be doing race for life, raised over 1300 for charity and at the top uni for my subject. I am a very healthy weight for my height and hardly get ill.
PE really doesn't matter when you leave school. Its not essential like english and maths, and tbh a good parental influence on healthy eating/lifestyle choices is better than any PE lesson. No one, unless you are going to be an olympian, is going to use skipping PE against you as much as they might rely on your SATs results.