Yes, nursing programs are *very* difficult, however one girl's idea of academically challenging is a cake walk to another. There are those who came out of high school and or first time around in college with barely a "B" or even "C" average that were straight A nursing students. Some the other way around.
Surgical techs do not make as much as RNs that one knows. Average starting salary for a ST is $39.000 (see: Surgical Technologists : Occupational Outlook Handbook : U.S. Bureau of Labor Statistics
), whereas here in NYC new grad RNs start at the mid to low $70K/year.
Most of your time as a ST will be spent running, fetching, setting up, and assisting the physicans and nurses with very little of the "caring for people" aspect many state as their prime reason for wishing to become a nurse. All that running about means you will be on your feet a good part of your shift. Don't know your stamina level and more importantly how your legs are, but plan on making friends with a good pair or two of support hose. *LOL*
Unlike the nursing staff on the floors STs will have more exposure to physicans and leave us say not all surgeons have taken crash courses in congeniality. Like the delicate hot house flowers some are they tend to have meltdowns and it tis often the nursing/support staff that bears the brunt.
If your duties include scrubbing, then a strong bladder is also a requirement.
OTOH has a RN even starting out in one's mid-sixties or so (it will take you at least three to four years to complete a program), there are positions out there that aren't so physically demanding as bedside nursing. You will have to gain some experience perhaps for some but off the top of my head being a "school nurse" comes to mind.