I feel like people rely on me a lot and its beginning to get stressful. I work two jobs and at one of my jobs, our work schedules go out a month advance so if we want to ask for days off, we have to ask very far in advance. This can be difficult because people don't always know when they need time off that far in advance. So this leads to coworkers often asking me to switch shifts with them. My other job is at a parent co op preschool, so I'm only needed the days they don't have parents helping in the classroom. The lead teacher doesn't always know ahead of time what days parents are helping. So I usually don't know what days I'm working there until the last minute. On top of that, I teach a Saturday night preschool class at my church at least one Saturday a month, usually 2. I have the same problem there that I have with my first job. People constantly ask me to switch Saturdays with them because something comes up that they didn't know about ahead of time and they can't teach. I didn't mind covering for people at first but it's getting to be too much. I never see my friends anymore because I never know ahead of time if I'm going to be working which makes it really hard to make plans. I basically have no life outside of work. I'm not trying to be selfish. That's the last thing I am Because I feel bad saying no when people ask me to switch shifts or Saturdays. But I feel like I need room to breath. I would appreciate any tips on how to get my priorities straight and how to say no in a way that won't hurt people's feelings.

Say no (nicely and politely). Set boundaries. Don't try to explain. Don't makes excuses. Just say, "I can't work for you then."

IT'S YOUR LIFE! Why LET people do this to you? You need to decide what you will and won't do. Get rid of the guilt saying NO. "I'm sorry, I already have plans"

Being honest and straight forward with others starts with being honest and straight forward with yourself. Nothing wrong with putting you and your plans and needs first. Why be guilty because you cannot help someone else's needs and priorities?

Learn to say NO in a nice way and lose the guilt because after all, they will figure out how best to handle their own business without you. That helps them better than you ever can.

If you have to defend yourself in court, your lawyer will tell you to keep it SHORT and just answer the question in the minimum words possible.
Anything extra is a foot in the door.
It is not impolite to just say no, sorry.
If you want, keep a schedule on your phone or in a little pocket book, say 'let me look...' then 'sorry, I can't.'
THE END!

I like Joys idea, that way no questions will be asked, you checked, it's not possible, the end. Even if you can do it and just don't want to, they won't know, they'll think it's just a scheduling conflict.

I agree, just start saying no. Ask one of them to switch with you, and see if they would be helpful (most likely not)