Take a blood sample

Usually I work in the laboratory as a medical technologyst.
My major subject is cytology.So I spend most time with a microscope.
But three or four times a month I do a different job.
That is "take a blood sample".
It is a hard work.
If it successes to get a blood sample at one time and less pain,
I feel very satisfied and confident.
However if it fails, I feel like being thrown into the abyss of despair in a instant.
I am deepley depressed because I am very sorry for the patients.

Before I started to do this job, I studied which blood vessels are more sutable for injection.
Then I practiced with a rubber arm how to inject a needle.
After this, I practiced real arms of my colleagues many times.
But the real is not easy.
Patients' blood vessels are various.
It runs straight or cross,visible or invisible,hard or soft etc...
I am somtimes at a loss.

My teacher said "you have to learn a lots from the patients".
This is the most impotant thing I should remember.
I need to practice more and more,
but I should not forget to thank for the patients who give me the chance to learn.