Hi Sara...
Congratulations...you too are doing so great there!

And good going, going right back to your quit, even tho you had that one cig! For SO many people, one cig, and that's it!!.... they don't quit again for years!! (That was me, many, many times!)
As for your endurance...give it time... your lungs need time to heal, but it will improve! Just keep up the exercise, good diet, vitamins, etc., and most of all--JUST DO NOT SMOKE!!!
BTW, how did you quit...with nicotine replacement, or did ya go "cold turkey?"
Yes, that's a good way to look at it...saving the money can help pay for the more IMPORTANT things in life, like GAS, and COLLEGE. Way to go...you have a great attitude about quitting..you have to in order to really quit!!!
Deda