Why do i get nervous when my favorite MMA fighter Lyoto Machida is gonna fight?

Im 14 and a boy lol but idk when my favorite fighters like Machida and Silva fight my heart starts to go all fast like i think there gonna get knocked out i was devastated when Machida was knocked out by Shogun and when he fought Rampage i was nervous but i know he's a good fighter and all he was champion but i just get nervous how can i stop feeling like that i dont like it like when i heard he was gonna fight Rashad Evans at UFC 133 i couldnt sleep all night cuz that fight is like in 2 weeks but now Tito is gonna fight Rashad and than Machida gots beef with Dana White cuz he wanted more money to fight Evans but not to get off topic how can i stop feeling nervous?