Do long distance relationships work?

i am 16, my boyfriend is aswell. but he lives about 45minutes away. and before you say 'that's not very much' it is when you cannot drive. he sometimes takes the train down to my place, and i do too. but it's difficult, do you reckon that i'll work?! i am very keen on athletics, and he's amazing at it, we go to different clubs though, so i see him at the meetings. but other than that i see him like once a month, twice if i'm lucky. we've never lived nearby. we meet through athletics, which i guess is quite nice. i love him and he loves me. how much longer should i expect it to last if we've been dating for 5 months?