You don't need to be soft to practice yoga. Continuous yoga practice will make you softer, more open and more flexible. Not being soft doesn't mean you can't practice yoga. Yoga will help you become softer and stronger. Just take your time when you start practicing. An important part of yoga is to listen to the body's voice and avoid injury. If you are not flexible, you can borrow yoga AIDS, such as yoga bricks and yoga belts, to make the pose easier.
Many people think that yoga is stretching, improving flexibility and increasing strength. Although you can get physical benefits through yoga practice, like other sports, yoga is very helpful to mental health and spiritual practice. Besides yoga, there are conscious breathing, meditation, mindfulness, purification, body awareness and so on. Yoga is a combination of life and life, not just physical health. Learn to listen, don't be too demanding and pursue the beauty of yoga style, do what you can, and learn to listen to your body voice.