Living frugally is an all-encompassing lifestyle that includes not just the money you spend, but the way you conduct yourself in regards to your other resources: time, energy, and belongings. In this case, the importance of saying yes is pretty powerful when it comes to spending those other resources; there are certainly times to say no, and while yes seems to be much more difficult for people to say, it can give you the push you need to get ahead. Knowing how to say yes is a crucial skill.
Build connections by saying yes. Volunteering a few hours of your time on something you find unpleasant may not sound like a great way to spend your weekend -- but when doing so puts you in contact with higher-ups in a field you'd like to work in, there is no good reason to put your own comfort first! When you say yes, you can be putting yourself in a position to build bridges you would never otherwise have the chance to create.
Discover things about yourself by saying yes. Don't shun new opportunities just because you've never tried something before. When you say yes to an activity you haven't participated in or a project you've never headed up, you can learn a lot about yourself and your interests -- valuable information you can't get without practical application and searching. Granted, you don't want to sacrifice your priorities to do so, but if you value self-knowledge, saying yes to new things is a great way to go about finding it.
Get opportunities for free things by saying yes. Volunteering often has perks beyond feeling good when you help someone else and doing good for the environment or community: you may be in for some sort of discount or reward if you put in a certain amount of time. By the same token, saying yes to new work might allow you to combine some things you're doing now and actually give yourself a raise.
Create bartering options by saying yes. Your yes can be conditional -- if you say yes to what someone is asking you to do, you get something in return. While this sounds a little rude, it's actually a very practical way to barter your services for the things you need.
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