Discriminate against obese without realizing it?

Having always been an obese person I know for a fact that in my life my weight was always an issue in many ways however I have always had a job and surprisingly enough I have been hired for all jobs I applied for. My belief was to always hold a job and I think that kept me ahead of a lot of others. So work wise No I was always taken seriously and never treated negatively. I was able to work hard however. Just last week while shopping at Walmart I noticed an extremely obese girl I would guess in her twenties working in an isle pricing and coding items while sitting on a chair that did surprise me actually that she had been hired, but again she was very busy and appeared to be doing a lot of work. I've never had to sit and work thankfully but it was hard not to notice her.

In a lot of ways obese people really get discriminated. For one if I were the employee I will not hire obese person because it is already given that he is not healthy or even if he is healthy at the time of the interview, time will come that he will have health issues unless he'd do something to reduce into normal weight but what is the possibility of he doing that? Also obese people are mostly lazy. Well there is so much fat in their body so their tendency is to be sleepy all the time.It may not apply to all but to many however. That is proven. So even if I do not want to discriminate I can't help doing that.