Pain is a limiting factor. It literally stops us from doing something so that we don't make the problem worse (in some cases extremely worse). This does not fit the old adage 'More Pain, More Gain'.
The International Association for the Study of Pain's widely used definition states, "Pain is an unpleasant sensory and emotional experience associated with actual or potential tissue damage, or described in terms of such damage".
Therefore, if we can understand such things as pain being such an unpleasant and emotional response then we can be on our first step to healing and repair. Pain motivates people to stop doing activities that promote pain. This protects the body from further damage and allows the body time to heal. If pain is ignored inflammation rises throughout the body and, over time, WILL cause other more serious conditions.
Treating just the pain alone doesn’t necessarily mean that the body is healed from what initially caused the pain. For example: If a someone comes in with shoulder pain, the source of the pain could be from the shoulder itself or referral pains from other areas of the body; the liver, pancreas, structural/postural problems and etc. If we only treat the shoulder (and pain levels reduce) without proper testing, we might be missing something vital! The deeper problem still exists and will continue to get worse over time, thus causing pain later in life.
Pain is a perfectly designed mechanism that is in play so we don't make our bodies worse! Our goal is to make sure we help each individual understand pain and how it is affecting their body specifically. When the true source of the actual or potential tissue damage is found and work is performed to resolve it, then and only then will the pain have a vanishing effect long term.