Hello, so I've just started about a week ago. I ride this one mile stretch of road back and forth, it's the only place I can ride. I ride a Trek 4300 mountain bike.

-Thursday I did 12 miles 40 minutes.
-Friday it rained
-Saturday I did 10 miles -ran out of daylight, not sure the time.
-And today I did 14 miles in 55 minutes with a "put the chain back on" stop, "manually put the chain back on the first sprocket stop since it wouldn't change" stop, a water break, then another water break and a phone-call.

I would just like to know how my performance is for a beginner and given that I'm on a mountain bike. Also, should I get one of those heart-rate monitors to make sure I'm not slacking off or going to hard and to stay consistant during the ride?

-Thanks!


EDIT: I'm going to start going to the GYM with my brother, he's pretty much as knowledgeable as a personal trainer. But anyway, at the gym they obviously have lots of weight machines, a pool, and I think they may have bike trainers. Is there anything that will help or hurt my cycling? Is a trainer better than actually going out side to ride? And what about Swimming? And just so you know, I'm 6'2-3" 175lbs. and 16

-Thanks.