I'll start this by saying I carried this way for way too long. I also thought it was comfortable. But with the right holster and belt, you'll be much better off comfort wise. But that's not the biggest issue. Re-holstering into a holster should only need one hand. Having to take the holster off, put the gun in and then clip it back on to your belt is bad. And please for the love of all things good, don't use the muzzle if your pistol to work it back into the holster while it's on your belt. Those holsters also have next to zero retention. Chances are if you're rolling around on the ground or running for all you're worth, that gun won't stay in place. And if you're doing one of the above, chances are that you'll need your pistol too.
My recommendation is start with a good belt. Not a heavy duty Walmart belt. A real gun belt. I and other here really like the Daltech Force Super BioBelt. They run about $60 shipped. Beltman, Galco, 511 and a bunch of others make true gun belts too. The belt is the foundation for comfort. Next will be a good holster. Since you have a Shield, you have lots of good options. Look at Alien Gear, Galco, Crossbreed, Nate Squared (N8 2) or any other of the numerous quality holster makers. Personally, I prefer a kydex, leather hybrid like the Crossbreed or Galco IWB. But you will find one that works best for you.
One thing these have in common is they are not cheap. Yes, you will spend some of your hard earned cash on good equipment. But in the long run, it's worth it. If your rolling around on the ground because some crackhead jumped you and you reach for your gun and it isn't there, I'd bet you'd pay $150 to get out of that situation. And it will really be more comfortable wearing everyday.
Just my
Repp'd and agree 100%.