I set up a nice little business after retiring and getting bored after a year or so.
It grew too big and a few years ago I throttled it back to a position where it suits me better.
As with any new business venture, large or small, you need to be 100% committed for it to flourish as well as being prepared for the amount of your life it consumes - especially within the formative stages.
As
@screenman has already alluded, many small businesses fail quickly. In my experience this is either because they are under-capitalised, the rose tinted market simply doesn't exist or the owner(s) simply don't have the skillset to actually sell their product or service.
Notwithstanding this; it can be great fun and in truth I've derived more pleasure from owning this little enterprise than I found in the considerably chunkier corporate roles that I held in my 'old' life.
Good luck if you do give it a shot!