Why is it important that obligations in any contract be faithfully fulfilled?
Laws are enacted to have order (or require the performance of a particular action to achieve the same) Since the terms and conditions of a contract are considered the governing laws between parties, it is necessary to faithfully fulfill one's obligation, that is, to avoid the occurrence of dispute. Hence, why do we have to fulfill our obligations, that is to achieving order between the parties to the contract.
How do you apply the laws on obligations and contracts to everyday activities and business dealings?
We apply laws on obligations and contracts unconsciously to our daily activities. One will not notice that in performing a simple common task you have applied several principles on obligations and contracts. Like, for example, buying a piece of pandesal, the buyer will offer to buy and the seller will accept. At this point, once the seller and buyer agrees to the object and price, and their minds have met; each of them will not just rescind or refuse to comply. Even without knowledge of law, one will not just back out from the perfected sale.
Then, after the perfection of the contract of sell; unknowingly, they will go on to consummate the same. The buyer will hand the money and the seller, in return, will hand over the pandesal. A clear example of reciprocal obligations, isn't?
If the money given is more than the price of the pandesal, the seller will give the change. That is because he knows no one should be enriched at the expense of another; hence, he has the obligation to return what is not due him. Likewise, if what was delivered to the buyer is more than what he paid for, he will return the same under the same principle, creating an implied obligation to return.
In a simple, but very common, transaction, the parties are not aware that they are applying the basic principles of law on obligations and contracts. They might not be well versed, or even, have not had any formal education, yet they apply these simple principles of law unconsciously. Thus, If you ask: how we apply laws on obligations and contracts on our daily activities, we apply it unknowingly, but instinctively, depending on one's value.