She's right or maybe just try to play the rhythm part and when you think you're ready for COB's Lead part, try it !
When I started to play electric guitar, I first started with Green Day (I fucking hate them but it's a good start) then I played a little bit harder stuff and so on... Just don't give up. Now I've been playing for one year and a half and there's guitar player's who's been playing for like 4-5 years and they're looking at me playing and they say "OMFG you're way better than me !!" (But I truely don't know how I got this good...
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XD). Maybe a proof that harsh work is a good way to play harder stuff ^^ !