Body fat percentage

12-30. I know, it's hard. But I went from 35 to somewhere between 19 and 22 in the last year, and I'm more than twice your age. You can do it.

http://lowcarbdiets.about.com/library/blbodyfatcharts.htm
http://www.livestrong.com/article/76266-good-body-fat-percentage/

It varies based on the person, goals, etc. IMO, having goals like that are fine as they are easily measured, but ultimately your goals should be based more on improving - being faster, stronger, leaner, healthier than you were last month, regardless of what exactly that means.

12-30. I know, it's hard. But I went from 35 to somewhere between 19 and 22 in the last year, and I'm more than twice your age. You can do it.

http://lowcarbdiets.about.com/library/blbodyfatcharts.htm
http://www.livestrong.com/article/76266-good-body-fat-percentage/

It also depends on your age and what your fitness goals are. Less than 25% is healthy but if a woman drops below the mid teens in percentage, it can have negative effects on your hormones & fertility. I'm over 30 and I have to watch mine carefully.