Knowing the requirements for a job before applying is always important. As a medical laboratory technician, there will be a great deal of time spent standing and moving/lifting equipment. When applying for a job that requires some physical exertion, most interviewers will address that need during the interview. If you are capable of handling the physical work, say so. If you feel you can stand for long hours, but have trouble lifting heavy objects, say that, too. It is always best to address these issues during an interview rather than omitting the information just to get a job. This would be a good time for you to express your understanding of the importance of self-care when working a job that requires physical exertion.