Just finished a BIO lab...practiced using a needle for IM (intramuscular) or SQ (subcutaneous) injections. It's harder than it seems at first. There's a certain way to inject the needle...you never want to put it in reeeeeeeeeeeeeeeeeeeal slowly, and then squeeeeeeeeeeeeeeeeeeeeeeeze like they do in the movies. You want it to be as quick and pain-free as possible for your patient.
Christ's death on the cross was not quick and painless. He suffered through the worst punishment the Romans could devise. Hanging on a cross was a punishment reserved for criminals of worst kind, and Jesus suffered greatly not just in the physical sense, but in His separation from God also.
An amazing thing about it though, is that Jesus suffered willingly for those he chose to save. A needle put into the arm of a young child may cause him pain and fear even if it is put in by a skilled health care professional. Needles are by no means pleasant, especially to kids. I remember I was never too afraid or averse to them, but I certainly can understand why there is such an intense dislike of them. Jesus did not resist His death, but went "like a lamb that is led to slaughter, And like a sheep that is silent before its shearers, So He did not open His mouth." Isaiah 53:7b. One can almost see a similar thing being said of a small child and a needle. Jesus suffered for us quietly, without complaint. What is the least you can do for Him? Well, to start out, love Him as your savior, above all earthly possessions and even your own life. Suffer the unfairness and hurt of life without complaint, thinking back to the cross, where the ultimate pain was endured meekly, by our dearly loved LORD!