Same here! I used to get up and go without thinking about it, but then life happened and I let things get in the way. Now my back has been hurting me and I know I have bad posture. I try to remember to sit straight and will fix it if I catch myself slouching.
You just have to practice good posture, when you feel yourself slouched, stand up straight,doesn't take long before you get use to it. But sometimes you always have to remind yourself. I use to practice poor posture till I realized how bad it looked.