Being "good at yoga" does not mean being able to do the most advanced version of every pose. It means working patiently and lovingly, wherever you are. Being gentle with ourselves means we are practicing ahimsa, or non-harm.
What I love about yoga is that it provides a format to make progress toward tangible goals. You see someone do a beautiful asana, and when you try it you just can't do it. But then you continue to come to your mat every day and practice, and you gradually get closer.
Whenever I remind myself that I used to struggle with Chaturanga Dandasana (aka low push-up), I am inspired to continually work toward poses that are seemingly out of my reach.
Last year, I made it my goal to achieve a forearm stand (Pincha Mayurasana). It's a fun, challenging, beautiful asana that requires building up a lot of strength in the shoulders, arms and back.
Here are some of the drills I incorporated into my regular practice every day until I was strong enough to support myself in forearm stand. Start by holding each pose for 30 seconds and increase you time by 10 seconds each week. When you feel ready, kick up into a forearm stand against a wall to start, until you feel strong and stable enough to hold the pose without support.
Remember to be patient, disciplined and gentle with yourself as you build the foundation needed to succeed in this pose. That's more important than the pose itself anyway!