When someone says "live a little" they mean it like "live a little more".

I mean ppl usually say that you're only alive when you feel good and bad emotions, and when you're hurting sometimes as well. So I assume making some mistakes, being wrong, feeling things, being exposed to stuff, that's all "living". And sitting in your room following daily patterns a lot, no change in behaviour or routine, that's all the "dying" part.

But at the end of the day it's all subjective and it really depends on your focus in life and your definitions.

You seem to show some of your self-image here (a concept that replaces the misleading "ego"). The short description you give seems to tell that this is attached to "the quantity of your doing". Hence the idea of "living = doing more = becoming more" vs. "dying = doing less = becoming less".

While there is nothing wrong with that in principle (heaps of books exist on the different philosophical approaches on this wider topic and yours is quite popular among certain cultures), we could without changing much arrive at a different but perhaps more satisfying conclusion.
The change is from equating "living" to the experience of exercising our body and mind, to "living" being the experience of purely inhabiting and owning that body and mind. -- That would probably be what people mean when they seemingly tell you to paradoxically "live a little" (implying to mean "live a little more") by "doing less". Which, when we really concentrate on enjoying the pure experience will not actually mean that we are just idling but it would mean we would be less occupied with exercising and more occupied with observing the living (or observing the feeling of it). Whether we actually do physical/mental exercising or not does not really matter. It's just more easy for many people to do the observing while they are "idling" or "meditating" in a still way, but any way that fits a specific person is good. We might be surprised by how active we are when doing that.

That way we could arrive at the insight that "doing less" does not equal "becoming less" (perhaps even the contrary), neither that "dying" equals "becoming less". :-)

edit ... If we were to see "living" and "dying" purely as functions of an organism regardless of the existence of a self-image, then "living" would mean a sustained state of dynamic equilibrium whereas "dying" would be a transitory state toward non-equilibrium (that is decaying). Interestingly, decaying should then be a transitory state from being one dead organism into sustaining the equilibrium of living in other organisms (i.e. becoming the other); while there would be no transitory state toward becoming living (there's just a transition from being a single cell to being an organism).

Living is the continuation of consciousness, dying is the cessation (or interruption, or –more liberally– damaging) of consciousness.

But more to what you're talking about, when they say "live a little" they mean getting out of your routines and comfort zones, which IS an avenue for growth.

I'm not sure, as sometimes I wonder which one I am.