Unfortunately Tamm, this personal negativity is something that the individual has to work on themselves.
Try comparing your work to images in the magazines (the nice natural-looking ones not the ones that all look exactly the same because they are trying to emulate competition nails). If your work stacks up well against others (who are out there earning money from it) then for goodness sake go for it.
But remember it does take more than good nails to be successful. See my recent post about this. If you feel you really do not have the right personality for it and are unhappy when you work, then don't do it. If it's not fun for you then leave it alone. Seriously.