Strength, to me, is humility and having the heart of a servant leader, of not worrying what other people think. It is the ability and willingness to keep each other safe, regardless of gender. I see strength as being that of character, not body... strong enough to overcome gender stereotypes and simply be who you are.
For men, I guess that means being strong enough in oneself to be able to feel and show emotion without fear of repercussion, to be able to show one's vulnerability in a safe situation. For women, I would say the same, actually... to feel and show emotion *not* because it gives you a dramatic high and makes your heart pound (which is what I see many women doing), but because it reveals your vulnerability and need for others.
I respect a man's strength in being willing to ask for help, in not being arrogant and assuming he can fix anything, in being able to surrender when he feels weak... basically, for having respect for others and for caring for himself instead of bottling it all up.
I do respect women for being strong, but not necessarily physically (and yes, I do work out regularly and love the feel of my muscles, but I don't see that as "strength" even though I can kick some ass
). For women in general, I think they are strong if they can be themselves without sacrificing any of their toughness to the social demands of femininity. If they can walk with confidence and know that they are loved and are capable of loving. If they know that no man is better than them, and that they are no better than any man. If they do not need to cling to other people in order to feel secure.
Just some random thoughts...