Answer:
perform the contractual duties, if a party performs there part of the contract, then they can discharge it at will.
Step-by-step explanation:
If you like football you must know who I'm talking about. It is normal that quarterbacks are signed for several years with a minimum guaranteed payment clause which determines a minimum payment in case the club wants to terminate the contract before its over. During the last few years one quarterback is notorious for signing contracts and leaving in the middle of the season (he took his team to the Superbowl, but was replaced in the final game, still his team won). He always walks out with his pockets full of money because as long as the other party (the club) fulfills their part with several millions, they can discharge the contract even if the other party hasn't performed.
The same logic applies to all contracts, if one party wants to discharge a contract for whatever reason, all they need to do is perform their part and that's all.