Girls should be motivated to take part in sports. Sports is actually a great thing and it also helps the body to relax, so yes, ladies should be motivated to participate in sports activities.
Are they not?
For almost all sporting events, there is a category for women, so I don't think they have been left out. If you continue to observe fewer women participating in sports, this may be a social issue driven by stigmas or beliefs around you.
The only recent issue I have seen is women in sports wanting to earn the same amount as their male counterparts do, which I am not against because they put in effort as well into their craft.