What are some ways to fix bad posture?

someone else had a posture question so I thought since I have terrible posture myself, why not ask for tips?
So my biggest problem is that I have a hard time keeping my posture in mind, lol my mom does call me out for my bad posture tho. But I have bad habits like constantly leaning over the desk when I'm at school even if I'm not on a laptop. Also my backpack is really heavy so I end up slouching a bit especially since I'm trying to get used to the weight again after winter break.

Not looking for perfect posture but just a way to improve my posture or a trick to keep posture in mind.
What are some ways to fix bad posture?
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