Question: A previous post ([What Is Energy? Where did it come from?](https://physics.stackexchange.com/q/3014/)) defines work qualitatively as "a process in which energy is transformed from one form to another form". And mathematically, work is defined as:

$$\Delta KE=\int\_{C} \vec{F}\cdot\mathrm d\vec{r}$$

But if you imagine lifting up a rock from the ground at constant speed, am I not doing work on the rock by converting the chemical energy stored in my muscles into the potential energy of the rock? I am confused because the kinetic energy of the rock does not change and yet I am still converting energy from one form to another, which is the qualitative definition of work. What's the right way to think about this and the concept of work in general?

Answer: 
The problem with work is the word we use for it. Since we work everyday, we're used to associate "physical work" and "effort", and that's confusing.

Physical work is a well defined quantity, but it needs 3 surnames, and this is usually omitted. You must specify these three parameters:

Work done [by some force] [on some system] [along this path]
------------------------------------------------------------

Note how deep is this sentence. Work is done by forces, not by people. You don't do work, a force does work, not you.

Plus, work must be considered on a system. If you lift a rock, you are doing possitive work on the rock. However, gravity is doing negative work on the rock.

$W\_{you}=mg\cdot h\cdot 1$; because $cos(0º)=1$

$W\_{gravity}=mg\cdot h\cdot -1$; because $cos(180º)=-1$

So the total work on the rock is $0$ and that's why you are not increasing its kinetic energy. If you perform extra forces, then you will accelerate teh rock ($F=ma$, you know). So you'll accelerate the rock and hence the KE changes. It makes sense.

But you have to realize that you are considering the rock as a well delimited system. If you include the chemical energy stored in your arms, then your system under consideration is not the rock alone anymore. Your new system under study will be the rock-person system, and then you have to consider ALL forces involved in that system, not just your arm.

In conclusion: work needs 3 specifications. You seem to be needing to focus on the "on what system" part.

Hope this helped
I think perhaps the easiest (perhaps way too didactic) method to understand it is in terms of currencies. For example, think of dollars (for potential energy), euros (for kinetic energy) and Yens (in the case of muscles chemical energy).

In the example of lifting up a stone (supposing somehow it was originally in motion), you are exchanging Yens for dollars (meanwhile increasing the stone's potential energy), but you do nothing with the entire system's total energy (no one is actually changing the total amount of euros in your pocket). In this simple
metaphor, your total capital is constant and therefore the Energy is conserved.

You can in fact think the total Work done as the exchange house total money exchange

Hope this is useful. Regards