totally with GS on the jealousy thing and the gym metaphor. in fact, i'll use a yoga metaphor...which i do a lot, as i am a yoga geek and have found that yoga has taught me gobs about how my mind works.
if there is a pose that you really HATE in yoga (and i don't mean it hurts you, i just mean it's uncomfortable or you've been working on it for a long time and you're frustrated with it), it means that it has something to teach you. instead of avoiding it, or trying to eradicate the feelings it brings up, force yourself to examine WHY you have those feelings. discover what makes you uncomfortable about it.
are you scared? go out on a limb and try it...worst case: you fall, you fail, you learn what doesn't work, and you try again.
does it cause pain? examine why...is it because of an old injury? are you pushing yourself too hard, too far or too fast? look for the place of balance between pushing and resting.
jealousy (like fear or uneasiness) is one of those tricky things that likes to hide its true motivations. picking it apart and addressing each individual aspect of it is where the learning lies! jealousy isn't something to eradicate, it's another opportunity to grow!