Being a hard target is more than just a mindset.
It’s also about physically being a harder target.
How?
Be smaller, harder to see, and protected.
Using the terrain to your advantage serves your desire to stay alive and avoid injury.
It can allow you to hide most of your body. This is concealment. It’s difficult to hit what you can’t see, so be unseen.
It can allow you to use stronger objects, like a vehicle engine block, to protect you from incoming fire. Even if an assailant knows where you are and can shoot in your direction it won’t necessarily mean they can defeat your protection. This is especially true if you are also hard to see and effectively returning fire.
It can increase the effectiveness of your return fire. Properly using terrain or a barrier as a improvised supported firing position increases the accuracy of your shooting. More accurate can easily translate to a quicker and greater effect on a hostile threat. Using support can mean the difference between round landing around a threat and forcing them to cover and rounds landing on threat and removing them as a threat entirely.
Using cover and concealment is fairly simple. Using them well requires some knowledge.
Remember concealment is non-protective. It is terrain that hides you and nothing else. A door can be concealment, a pile of cardboard boxes, a curtain, none of which will stop or deflect incoming fire.
Cover is protective. Large, strong, dense objects that will catch or deflect gun shots. Concrete barrier, engine block, defilade from micro terrain will decrease the likelihood of taking a hit because you’re much more difficult to hit.
Know the difference.
Additionally know just how much of you is covered or concealed. Be aware of how much space you occupy and what on you is and isn’t protected.
