It can be done, but it's not easy.
If there's a flea/farmers market near you, rent a space. Have about 20+ different images, in a variety of sizes, matted and bagged. Frame a few. Be there every weekend. It may take awhile to start selling but, with time, people will buy. You won't get rich, and may only recoup your material cost, but you never know...
Years ago, I started selling my work at a flea market on Cap. Hill, in Washington DC. The space cost me $20/day. I didn't sell a thing for 5 weeks. On the 6th week, people who had been looking the previous weeks bought. I sold about $250 that weekend. The following weekend it went to $400. By the time I stopped setting up there (to do Art Festivals), I was averaging about $750 per weekend. I also booked the occasional portrait session, adding to my total.
If it's something you'd really like to do, do it. You won't know until you try. Do you really want to be sitting in your rocking chair, in your old age, thinking "what if"?