Hello all. New to forum and after a few tips regarding building up my fitness. I have been away from biking for about 10 years and have just bought a new bike (Giant Talon 0)for trail riding. Went out over the week end and my legs where like lead after 10 mins on the bike. :D. Any advice for building up my fitness. I would like to ride longer than 10 mins before melting into a fat heap.