如果是书面用途，可以写 Due to health issue, I delayed one year entering the school.
如果是跟朋友说话的时候，可以说 I entered the school one year later than others because of health problems.
英文：Due to physical reasons, announced to withdraw.
或者：Declaration of withdrawal for medical reasons。
1. 身体的/生理的原因。例如：Emotional or mental problems can arise from a physical cause. 身体上的原因可引起情绪或精神上的问题。
2. 物理原因。例如：There may be a real physical cause for this change. 这种变化或许有其真正的物理原因。
Because of his physical reasons, he is now applying for a drop out of school
I can't imagine why you are so busy.I believe health is more important than work,because there are endless works,but life is limited.Perhaps my words are very direct,but I do think it hurts.
seriously sorry,i can't attend the scheduled company-meeting because of my health problem