Im 17 years old and i just got a mountain bike yesterday and also a speed and mileage odometer. I like to bike everyday that its nice. I dont ride professionally just for fun. From the time I left my house at 4:30pm to when i got home at 2am, i rode 65 miles, including breaks. Is that a good amount? I didnt feel tired at all when i finished, just thirsty. What is your opinoin?