I know that I'm pretty new here, but I thought that I'd share a story.  I worked last summer at a strawberry type farm.  One day some of us were hoeing, and we needed the hoes sharpened.  So the older guy ( approximately college age) sharpened hoes for us on the bench grinder.  We went out to start while he did a couple more.  When he came out he said that he just "got kicked by a horse".  The grinding wheel had broken in half and he took a half in the chest.  It hit on the curved edge of the disc, and knocked him down, but he ended up being alright, just sore for several days.  It just emphasis what I've seen here in other threads about STAYING OUT OF THE PLANE OF ROTATION.  Had that wheel hit him with the corner it could have been very bad, I guess it could have even like it was.  So... be careful: tools carry, almost by definition, some element of danger and using them reasonably carefully is part of being responsible.

Before using ANY grinding tool, stand out of the plane of rotation and let the grinder get up to speed, and stay there (at speed) for a minute or so.  How far do you stand back? The answer is a SAFE distance. Who knows if the grinding wheel or disc was dropped or had damage while you were away. Or if it is just time to come apart.

You do know that grinding removes metal. Why not learn to sharpen the hoe, mattock, axe, etc on the anvil? No metal lost when sharped on the anvil.

I hadn't thought of letting the tool run for a minute or two, now,the question is: will I remember when I go to use the grinder?  I forgot to mention the size of the wheel, it was a 6-inch wheel.

Put a tag on the switch or on the motor reminding you to use caution when operating this tool, and to let it run for a minute or so before using..

First wheel that self destructs and send pieces in all directions at warp speed will etch the experience in your memory.

Always readjust the disc catch guard and the tool rest as the wheel wears down

Nice thing about the  belt type grinders, when the belt breaks it basically just falls off. no hand grenade effect to fear.

We had a bad batch of 220 grit belts; but we got them pretty much for free and some were good....they would whap you on top of the head when they let go.  We ended up creating a guard for a Bader belt grinder to catch the belt if the glue joint failed.

Always complete a visual inspection and ring test before mounting a wheel. If you find a cracked wheel, then break it so it can never be mounted, but don;t discard it, I use the broken bits to dress mounted wheels and in the process redress the broken bits to use as sharpening stones, which can be very handy if you need to keep touching up the likes of hoes in the field, saves taking them for sharpening so often!

I have a piece of a broken grinding wheel at the forge. It is great for brightening the stock so you can watch the colors run when tempering metal.

And traditional, though a brick is also mentioned...