It’s been told to me that part of the reason we don’t buy things, engage in certain hobbies/entertainment, etc on the Sabbath is because we are, in effect, causing someone else to work on the Sabbath, which is supposed to be a day of rest. My place of employment requires me to work every 12th Sunday. It’s not something I look forward to, but I know when it’s coming. If I try and get one of the other employees to cover my Sunday shift, would that not, in effect, be causing someone else to work on the Sabbath? Even if I quit my job and they replaced me… again, would I not, in effect, be causing someone else to work on the Sabbath? It seems to me like I’ll be breaking the law of the Sabbath one way or another no matter how I try to get around this. I’ll either be working on the Sabbath myself, or I’ll be causing someone else to work on the Sabbath in my place.
Often the easiest commandments for us to obey are the ones that can become mindless habits. Unfortunately, the underlying principles of these commandments are intended to focus our thoughts and attention – requiring us to be mindful rather than mindless. Honoring the Sabbath is one such commandment.
The purpose of the Sabbath is for each individual to turn his or her focus from the day-to-day towards the Father that created us (Exodus 20), the Savior who delivers us (Deuteronomy 5), and the Redeemer who saved us. To assist in this focus, we do what we can to remove distractions that would steer our attention from the Lord whose day it is. Each person and each family needs to come up with their own guidelines for this. Culturally, many latter-day saints refuse to work on Sunday so they can have that time for private and public worship. Valuing that sacred time, they also strive to reduce the demand on others’ time away from worship. This feeds into your idea that we don’t shop on Sunday because we don’t want others to work, but I must repeat that the purpose of the Sabbath is not to refrain from or prevent work. The purpose of the Sabbath is to worship. As an individual I will worship. And I will do what I can to aid others in their worship.
For your specific situation, you need to decide for yourself (with the Lord’s counsel) what your guidelines are for Sabbath observance. If you are concerned that by taking Sunday off, or in quitting your job you are forcing another to break the Sabbath, let me assure you that is not so. In order for someone to work on Sunday there has to be demand (otherwise the position would be unprofitable). If you don’t want to contribute to that person breaking the Sabbath then don’t be a part of the demand. In order for someone to work on Sunday there has to be an employer. If you don’t want to contribute to that person breaking the Sabbath, then don’t hire an employee to work on that day. That is the realm of your influence and the extent of your culpability.