30 minutes 3 times per week is the minimum consistent with good health, and this is the default recommendation from Spark (how many calories this translates to depends on your current body weight).
Presumably one of your goals is to keep the weight off in the long term. From this perspective, it is important that the exercise targets you set are realistic and sustainable. Going suddenly from zero to exercising 60 minutes a day 7 days a week is probably something that is not going to 'stick'. A more moderate goal that you can achieve is probably going to be more helpful than a super ambitious one that you can't. Many people gradually increase their exercise target as they get fitter, and establish exercise as a regular part of their overall lifestyle.
While exercise has many significant health benefits, and should be part of any weight loss program, for the most part, weight loss is 80% nutrition, and just 20%.
Certainly I exercise a lot more than Spark's default recommendations, but this is for fitness, rather than weight loss reasons.
The reasonable man adapts himself to the world; the unreasonable one persists in trying to adapt the world to himself. Therefore all progress depends on the unreasonable man.
| current weight: 178.0