I originally started giving blood to get over my hang-up about needles. I can cope but I wouldn't say it is a pleasant experience.
The inside of my left elbow is purple and yellow this morning. Makes me look like some half-wit heroin addict

I am on some powerful pain relief which can cause liver and kidney damage so I have to have blood tests every 6 months.
A few years ago I had a totally inept phlebotomist who couldn't find a vein and so my arm was poked full of holes as she probed for the elusive vein. She eventually got the blood flowing, but then couldn't stem the flow.
The end result was a badly bruised inside to the elbow with blueish, purple streaks radiating down my fore arm.
It was one of those rare hot and sunny summers and I was wearing shorts and T shirt. I was also suffering from partial paralysis and under the influence of the aforementioned powerful painkillers and was very unsteady on my feet. Inevitable I was stopped by a copper who thought I was a junky. My indignant and flowery rebuttal was not fully appreciated and nearly resulted in an arrest.
Spare a thought for diabetics. My wife is a type 1 diabetic and has to inject herself 4 times a day and do at least four blood test to check her blood sugar levels. Needles play a big part in her life.