How Growing Muscles Work., How long i supposed to excersize on certain muscle daily

[MrVeg]

I know if you exercise your muscles get tired and break a little everywhere along the point where most pressure applied and when it heals itself you get additional muscle mass.

Now i trying to understand how long i should exercise on certain muscle daily to get best results (i need agility/endurance , strength more than and size and looks)? I usually do it until i fill i cannot do it no more, but i found that i can actually do it for hours (not because its easy) i just stop because its too time consuming. I currently working on my arms only with 5lb dumbbells (i find that this is best weight for me now).

[BartPimpson]

(i need agility/endurance , strength

But those are three very different things. For endurance, you'd train for a long time with low weights. For strength, you'd train for a short time with heavy weights. For agility, I don't think you'd do weight training at all.

[MrVeg]

But those are three very different things. For endurance, you'd train for a long time with low weights. For strength, you'd train for a short time with heavy weights. For agility, I don't think you'd do weight training at all.

Well okay anyhow i need to be physicaly capable e.g. running long time and being generally strong, i heard having too many muscles makes you go tired faster.

Anyhow i need at least some muscles now cuz i dont have any on my back and front torso at all! Can you please tell me about length of exercise on one certain part of muscles? When is the right time to stop will doing it longer give better results or just waste of time?