Hi,
you dont need to be so worried about his weight too much. See below:
- Labrador Dogs 60-75 pounds (27-34kg.)
- Labrador Bitches 55-70 pounds (25-32kg.)
- Some males can grow to 100 pounds (45kg) or more.
He is still young and will grow into his skin especially when his muscle tone forms as he gets older.
you could try walking him for 30 minutes, three times a day instead of trying to make it an hour walk, twice a day. as he is from a rescue shelter he wont have had a lot of exercise like you would think.
he wont be used to all the walking, so you need to be patient and buid his walking times up, then after a month or so, try walking him for an hour a walk, twice a day.
how many treats do you give him when your training, on average?
you dont want to be giving him too many.
i am training my 9 week old rottie at the moment and she is only being given a small amount of her daily diet at the moment as a treat when she does something right, so she doesnt get fat and because she had an upset tummy, but anyway they work the same way.
hope this helps, let me know if you need any more help with anything also training methods if you need some tips!
im always here to help!