Do some stretching after your walk. I don't ever stretch until I've warmed up some, so if you want to stretch "before" your walk, at least walk 3-5 minutes before you stop and do stretches. You can stretch again after. Even if you only do a few exercises for a couple of minutes, do SOMETHING!
Comfortable at this size/weight (I really don't want to buy size 0 jeans).
It's not about "weight" or the number on the scale. It's about lean muscle mass and body fat percentage.
At 125 I was a size 8 (after I lost 100+ pounds over 1.5 years).
At 135 I was a size 6 (maintained for several years) and over 28% body fat. I had 97 pounds of lean muscle mass and felt skinny fat.
Now at 140 I am a size 2 and have the smallest measurements I've ever had since I started taking them around the age of 18. I'm at 25% body fat and 107 pounds of lean muscle mass!! I'm no She-Hulk, either.
Don't tell me you aren't losing "weight." That doesn't tell me anything. Tell me how much fat you've lost and how much lean body mass you've gained. Here's a good start to estimate: http://www.scientificpsychic.com/fitness/diet.html