Everyone comes to yoga with either muscular strength or flexibility as their strong point. What our bodies naturally excel at we tend to gravitate toward. For instance, if you've done a lot of strength training in the past you'll most likely tend toward arm balances and warrior poses. If you've done a lot of gymnastics, dancing, etc. you'll probably like sundial and firefly poses.
Some people come to yoga with a combination of the above. They might have more lower body strength and can do warrior poses all day but struggle to hold plank for two breaths. Or some have really long legs and tight hamstrings but very open shoulders. I've learned over the years that there are no hard and fast rules about our bodies except that we all have weakness and strengths in various areas.
It's also very normal to have one side of the body that is stronger than the other or one side that is more flexible. Beginning students often find that they are able to balance better on one leg than the other in tree pose. Over time the disparity will be less noticeable. Years of tennis created a twist in my pelvis that has gradually worked itself out since I began practicing yoga.
It's because of our weaknesses and imbalances that I often tell my students that the poses they like the least are the ones they need the most. (This statement is usually followed by loud groans.) This is bad news if you hate bow pose as I do. Yes, I confess it's not my favorite. The twist in my hips means that I struggle with my hip-flexors.
The exception is if you have an injury and shouldn't be doing certain poses or if the pose hurts. There's a difference between "hurts so good" and "hurts not so good" of course. The "hurts so good" feels like a really good stretch whereas "hurts not so good" feels like it's actually damaging your body. Often tendons and ligaments feel like they are about to pop out of the joints when you've gone too far in a pose.
The hurts so good stretch is also known as the edge in yoga. Teachers sometimes instruct their students to find the edge. This is the place in pose where it almost feels like it's too much but not quite.
The breath is a good indicator of how far you should go in pose. If your breath is even and effortless, you are probably at ease in the pose. If your breath is rapid and forced, you might be too deep.
The breath is also a good indication of how challenging a pose is for you. If you are consistently able to maintain a normal breathing pattern in pose it might be one of your strengths. Conversely is true also.
Since one of the goals of yoga is to bring the body back into balance, it's good to be aware of which poses come easy for you and which ones challenge you. Practice the challenging ones more often and you'll probably notice more changes in your body. I'm not suggesting that you can skip the easy ones but just don't avoid the ones you don't like.