JJ,
I was diagnosed T1 quite late in life (42) and went from being really healthy (I'm in the Army) to having a potentially fatal illness. My initial response was to get really into it and I read a lot of books and managed to keep my HbA1C really down. As time has gone on, my enthusiasm and control has not been as good, although I am still in single figures.
I struggle to remotivate myself from time to time, but in the end it has to come from inside of you. You have to want to improve. I guess with the dose of Lantus you are on, you may not be as fit as you would like to be and perhaps this also plays into variable feelings of self worth. Life is precious and is in our own hands to make the most of it. Doing more exercise will improve your BG control and make you feel better about yourself and your condition. I know that I am at my best in terms of control and feeling good about myself when off doing something like skiing, which really does burn off the carbs. However, don't go beserk as you will never keep it up. As with women and diets (usually about getting fit fot he bikini season) life style change is the only way to make a sustainable difference.
Today - I have started cycling to work again. It's only a mile of so, but i will do it twice a day in each direction - so, 4 or 5 miles.
The other thing I found that helped was stopping hiding away taking injections - I now do it wherever I am - restaurant, office etc. If people don't like it, they can look away. I do it straight through my shirt, which seems to cause no difficulties.
Good luck and don't give up - we can beat this thing.
Nigel