anyone who knows about working out...

[mysteryboy]

The thing with doing chin ups & pull ups only, you'll only become good at doing those exercise. Doing press ups for example will not get you a big chest, instead you will only be able to do a higher number of reps (Have you actually gained strength or simply become better at doing the exercise?)
Thats why variery is so important as your muscles get used to the exercises you do week in week out and stop responding to them.