Races
All my races have one of two origins. They were either created by Immortals, or have evolved to be like the Gods they follow. All Gods and Immortals were once mortals.
Created races, mostly the monstrous types, can't breed. So things like trolls, beholders, etc. are very rare and since most of their creators have also perished, they are also dying out.
Gods evolve into their beliefs so that orcs, for instance, were once human but their vicious, war-like, bestial natures transformed their gods, and in turn transformed them.
Encounter Breaks
Stub your toe. Walk around on it. Then sit down for a few minutes. Pain stayed around when you were walking on it, and went away when you sat down, right?
Same difference.
Healing Surges
Don't think of damage as damage or hit points as hit points. In fact, rename everything. Call Healing Surges just Surges. Call hit points Health. Call damage Threat.
Explain 'hits' as not causing actual, physical damage, but rather being close calls, minor scrapes, bruises, strain on muscles, forced movement, dust in the eyes, grunting, groaning... anything but major physical damage.
All of this threatens the character's health. Only the blow that knocks someone below 0 counts as actual physical damage, and even then, it's only serious damage if they die.
Imagine fireballs as wafts of flame, like a fwoosh of gas being lit at the stove. It could really hurt you, or it could just wash over you and just singe some hairs. Imagine sword blows as scraping off or sliding off armours and shields, but the impact is certainly felt. A massive axe crashing into the wall just above and behind the heroes head certainly shaved a bit off the character's life-expectancy, but didn't actually hit him.
So Surges are now not actually healing, but rather someone shaking off the effects, taking a deep breath and picking themselves back up to get into the fray again. As was mentioned earlier, John McClane or Rocky or any other action hero, are good examples of this.
Daily/Encounter Abilities
I explain this quite easily. It's really a level of difficulty thing. Although you may attempt something numerous times in a combat, the situation or your ability just isn't up to par all the time.
The time when you do pull off the manoeuvre, is basically when you're "in the zone" so to speak, and that may only happen once an encounter, or it may be so difficult that you can only seem to manage it once a day.
Tiered Levelling
IMC, the PC's are a step above the common people. They represent about 1% of the population who have both the resources, mentor, ability, and drive to go the extra mile and gain ability beyond the normal person.
They are like elite athletes. Sure, you run a bit you can get a 12 second 100 metres, but even if you train for your entire life, you'll never shave that down to 9 seconds. And let's face it, who has the resources to train that much anyway?
In this respect, most PC's are of noble blood, since they are the most likely to have access to the required resources. And the mentor is a big component. The mentor IMC must be of 5th-level in the class the PC wants to become. And the mentor must WANT to train the PC. He's not going to tell all his secrets to just anybody who comes along.
And that's just the heroic tier.
Only 1% of that 1% ever manage to get to 11th-level. Just finding a mentor of high enough level and of the right type. IMC, you need to find someone of the paragon class you want to train in, of at least 15th-level to train you. That is a very rare thing alone in my setting.
I explain the paragon tier as being beyond even the elite. They are the exceptions. They are the Einstein's, the Hitler's, the Madonna's, the Michael Jordan's, etc. People who go well beyond what even the elite achieve.
And then there's epic.
I explain epic as going beyond the mortal limitations of one's existence. IMC, you have to become an Immortal (not just immortal) to gain 21st-level. You are essentially super-humanoid.