Are you at a plateau?
Have you been working out a lot, with no real improvements?
I see people in the gym all the time who work out long and hard, but seem to be maintaining a status quo.
To develop real curves, you need to shock your body. If you are doing the same thing all the time, your body will get used to the stress of the workout and will no longer respond by further developing full muscle.
Supercharge your workout with Progression.
This method of training places greater loads on each working muscle.
There are three ways in which you will progressively increase the resistance you place on a muscle:
1) Do more repetitions with a particular weight than you performed the last time you worked out.
2) Do the same number of repetitions as in a previous workout, but with heavier weight.
3) Do the same number of sets and reps with the same weight as in a previous training session, but reduce the length of rest intervals between sets.