Is 58, 140 lbs okay?

Yes, if you are about 5' 5" tall. I suspect what you need is to gain some muscle. You can lose that fat with some vigorous dancing, or jogging if that's your preference. A lot of people trim down by walking, but they don't tell me how they did it. I trimmed my belly by switching my diet to all peas and beans. That's called the Daniel diet, from Daniel chapter 1 in the bible.