I know a few people who felt Yoga sounded a bit "soft" (I know it doesn't have to be) but for those who want something a bit more physical you might want to look at pilates.
"Sounded?" That word suggests that they have only read or heard about it, without actually trying it.
I wonder if they would consider the physical and mental development required to hold Mayurasana as soft?
Sarcasm aside, lifting is far more effective than anything else for building strength.