Relativity can be a bit of a daunting 'brain-breaker' when you're new to it, but in the simplest terms, you don't feel the effects of The Special Theory of Relativity at all - there's nothing to feel; in a way, that's kind of the point, but it's also why it can be hard to understand.
In your first example, you may experience time at different speeds between pain and pleasure, and indeed feel the difference in time, but it has nothing to do with relativity. In this instance, it's about your own perceptions. I've heard it postulated that adrenaline 'speeds up' the mind (temporarily), so you may experience more 'stuff' in the same amount of time than without the adrenaline (the theory goes that it's to help us make decisions quicker when we are in danger).
As an analogy, think of your brain as having its own clock ticking away inside that lets you know how much time has passed. When the adrenaline is released the brain clock speeds up, and after a minute, your brain clock may have ticked 90 times, whereas your watch will only have ticked 60 times - time seems to have slowed down for you.
You may probably have experienced this in a way that you've noticed before - the second time you watch a movie, some of the action scenes that in your memory felt like they "lasted ages" now seem a lot shorter. This is because the first time around, you didn't know what was going to happen so there was more adrenaline pumping, and your perception of time slowed down because your brain clock was ticking faster - it might have ticked, say, 200 times for the scene. The second time around, you know what's going to happen already, so there's less adrenaline, and your brain clock may tick only 150 times, and so the scene seems shorter.
Obviously, there's isn't REALLY a little clock ticking away inside your brain, but it's a handy way of picturing what's happening with your own perception of time!
But as I say, none of that is to do with relativity at all.
Your second example is trickier to answer as it combines motion with exertion, so I'll break it down.
First of all, physical exertion also releases adrenaline into the blood, so the 'speeded up brain clock' scenario takes effect. So yes, you may experience time running slower than normal. Again, though, nothing to do with relativity.
However, if you could run "very quickly" in physics terms (this means approaching the speed of light), relativity will start to affect you, but not in a way that you might expect.
This time, time really will slow down (nothing to do with adrenaline) because of relativity. Your watch will tick slower, you will appear to shrink, and you can start to experience 'events' at the same time that your friend, who is standing still, would say happened one after the other.
But the key part of this, in relation to your question, is that you won't actually feel any of this, because YOU are affected by it all. To YOU, your watch is still ticking at the right speed. To YOU, you are still the same size.
It will only be when you stop running and look at your friend's watch that you'll notice that time slowed down for you. Your watch might say you went running for 8 minutes, whilst your friend's says you went running for 10.
Now this is the brain-breaking part: Relative to your point of view, you really did only run for 8 minutes. However, relative to your friend's point of view you ran for 10 minutes. BOTH of you are right. In fact, as there is no fixed point in space, you can't even say which of you was moving and which of you was stationary: it's all relative, and that's why they call it the theory of relativity.
(I apologise if reawakeningk a 7 month old question is 'bad form' around here, but I felt that as the question was asked in fairly lay terms, none of the answers, though accurate, were explained in a sufficiently simplistic manner.)