...My problem is it always ends up like this after a week or two...
More than likely, this is a two part problem. The good news is that one part of the problem is fairly straightforward to solve. The bad news is the other one will take some time. Let's tackle the easy part first since it helps with the second one...
If the storage solution is not easy/convenient to use, it won't be used regularly. Having a spot for everything is good and all, but you also need to make sure that whatever solution you implement is compatible with your workflow. For example, a battery powered drill is generally a high use item in any shop. Drilling holes, driving screws, tightening hardware... a drill has a lot of uses in a variety of applications. It would make no sense to store the drill in the factory blow molded case 15' away from your workbench. You'd want it handy and easily accessible. Whether it be hanging on a hook near your workbench, or in a drawer of a tool chest next to your workbench, it should only take a moment to both access and put away the drill.
As you think about how to store items in your garage, think about how frequently you need to access them. High use items are easy to access and stay near the point of use, low use items can be in a box, on top of a shelf on the other end of the shop. This is obviously common sense, but I see a lot of people get this wrong - myself included. For years now, I've had my welder cart parked in a spot I have to walk by constantly and I just don't use it all that often. It should be in a corner somewhere, not in my main working area.
The second part of the issue has already been touched upon by others - you need to develop the habit of putting things away when you are done with them. I get it. You are trying to get something done and the wife tells you it's time for dinner, so you drop everything and head inside for the night. Come back out to the shop after you're done and spend 5-10 minutes putting things away.
One excuse I used to tell myself is that I might as well leave these tools laying out because I'll need them to finish the project I started. That ends up being a slippery slope and the next thing I knew, I was right back where I started. Now when I'm tempted to just leave a few tools out, I remind myself that it's a heck of a lot easier to put them back because then you will know where to find them.
Another excuse I used to tell myself is that I don't get a ton of shop time - the last thing I want to do is waste time putting stuff away. My perspective has shifted there as well. Not putting stuff away results in me wasting a bunch of time trying to find the tools I need when I do get shop time, which gets frustrating. Walking into a clean and organized shop makes for a much more enjoyable experience.
Apologies for the novel, it's just something I'm passionate about. I'll admit that my shop was in much worse shape than yours was when I first started getting serious about organizing. I'll also admit that I don't always practice what I preach and slip up in staying organized more frequently than I'd like. Do not take anything I've said as a criticism or judgement, instead, think of them as points to consider.
Remember, a well organized shop is a journey, not a destination.