Im not sure how anyone really know when they want to be anything other than intrest. some are interwsted in space and want to be an astronaut, some want to help people and become DR or Nurse. Some look at pay and decide based off income to be had. think Of all the hospitals in your area or the US if your willing to travel. Each hospital can have as few as 4 Biomeds or big hospitals might have 10 or more with some being working managers or lead Biomeds.
the answer lies within you .... biomedical engineer is a person who repairs medical Equipment. Very sick people and nurses depend on you to do a good job, be detail oriented, have integrity even when no one is watching.
There are plenty of bad biomeds in hospitals but if you can be passionate about repair and maintenance of much needed equipment instead of counting the minutes till lunch and be depended on to do a good job correctly then you will move up in this field eventually. There is lots of equipment to cover and they are always looking for good men to send to school on specialty areas like Dialysis,radiology, surgical equipment ... hope this helps