I break up my decluttering into small bursts. When I get it under control the little burst of cleaning are all I need to do to keep my home clean and tidy. Sometimes if I get behind I do one big deep clean to get it back to where the small bursts are all I need.
I do a bit every day. Paper work and recycling daily and bigger stuff weekly, plus monthly and seasonal clear outs
You can maybe focus on a different part of your room or house each day/decluttering sessions, or focus on different levels of organisation (e.g: first organise everything that is visible, then organise your drawers/cupboards, then rethink your room?). You can do it all in one go but you’re more likely to get distracted, or fed up. And also it’s just more of a daunting task. If you can do it, great! But if not, that’s how most people are xD.
Doing one room or one section of a room at a time is a chance for you to improve gradually. It’s difficult but keeping one thing clean at a time and building is the best way to start.