It is very aptly said that our fate is in our hands.
Yes. Not only the destiny that is determined by our karmas or actions in our previous lives, but also the one that we determine by the actions we do in our present life. Both are indicated in our hands. The lines in the palm not only indicate the fate, but also our character, our preferences, our relationships etc.
On one hand, where we hold our destiny we are born with, on the other we can have a look at the changing of that very destiny, and comparing the both, a good palmist can easily tell you what we are headed for. He can also advise as to what should be our future actions, indicating the necessary precautions in order to govern our life towards a happy, prosperous and satisfying one.