Hello, I need some help working out a fitness routine. I basically need help in working out how much i should do at the start and how to build it up, as I dont want to rush into a routine I am not ready for. I am 17 years old, weigh 11 stone and stand at around 5 foot 8inches. I have recently started exercising but before that (around 2 weeks), I did barely any. Luckily I have been able to keep in shape, mainly as I have a good diet. However I am unhappy with how fit I am in excercise terms and wish to push myself. My upper body strength does not seem to be too much of an issue as I can manage 50 press ups, 15 pull ups and 50 sit ups. However I am especially interested in improving excerices such as swimming, cycling and especially running. At the moment, I would say I could run about a kilometre before i need to stop for a breather and walk for a while. I went swimming and managed 50 lengths however I needed to take about a 10-15 second break every time i got to the other end of the pool, which was a bit embarrasing as old ladies swimming near me kept plowing through like steamrollers. I know it is not wise to start doing too much at the start, so any advice about how i should start would be great. I have given all the information I could think of, however if I have left anything out just ask. Thank you!