I think if the only success stories you've ever heard are with "extreme exercise" consisting of burning 1400 calories per day, then you haven't spent much time on these message boards.
In my life, I have 4 (personal) friends (one is my husband) who lost 40+ pounds and have kept it off for 4+ years. I, myself, have lost 80 lbs and kept it off since 2011. NONE of these "success stories" consisted of that much exercise. Not one.
One of these people lost 45 lbs with no exercise at all. She's active, but no organized exercise at all.
That said, exercise made it much easier for myself and my husband. Not only did we burn the calories, we also built the muscle. Not to mention the confidence it builds, the friends I made to stay motivated and the mood lift it provides. For me, personally, fitness/exercise are essential to maintain my weight loss. I had knee replacement surgery in December and was unable to exercise - still can't do much - and my motivation is in the dumps. My depression is lurking, I'm binging more and I'm just...restless. I've gained a few pounds back, nothing major and I'm not worried about that - but I am worried about another major depressive episode.
Just so you know, my normal fitness routine consisted of 3-4 gym workouts per week and according to my HRM, I burned 500-600 calories per session. I also did a lot of walking on my lunch breaks - normally 30-45 minutes and that burned a couple hundred more, but I only did walks on days I didn't go to the gym. I had some days where I did nothing.
IMO, the most important element of weight loss and maintenance is patience. You say, "I only 9 lbs in 3 months" and I'd say, "I lost freakin'
9 pounds in
3 months! Woohoo!"