I also am in a job that requires heavy lifting and have back problems. I work in a University bookstore. I finally had to give up my receiving position and just work light duties for a time. Now, I work strictly on cash and lighter lifting duties. I understand how you feel, but remember NO job or career is worth ruining your back over! There are other options open for you especially in your field. Also you could return to college or universtity and take more Sciences to expand your credentials. My best advice is to go easy on your back, look at all your options and go from there. I hope this helps.