It is vitally important that you not base your workout on BMI.
Please read Slate's excellent discussion of how BMI came to be used to poorly and NPR's 10 Reasons why BMI should never, ever, really-don't-do-it, never be used for one's self-image or exercise goals.
BMI is not a valid way to measure your fitness or body. It is not useful for that purpose. Using it to measure how much weight you should lose, or how many calories to burn, is a surefire way to disappoint yourself.
Examine.com has a good overview on the validity (and lack thereof) of BMI, which can be summarized thus:
If you are normal weight or overweight according to BMI (18.5-29.9) there is still a chance you are actually obese, and thus is primarily due to low levels of lean mass (muscle, water, and glycogen).
Outliers to this dataset, those who have enough lean mass to be classified as obese by BMI but not by body fat percentage, are far and few in society. These persons would normally be highly active athletes or dedicated 'weekend warriors', and it is unlikely sedentary persons or those with infrequent exercise habits would be these outliers.
Instead, measure what you want to improve. Want to look better? Get a camera and a tape measure and track how you look (with consistent clothing, pose and lighting) and measurements of your arms, legs, hips, and waist.
It can also be more productive to set a performance goal. Good goals can be based around time ("run a mile in less than 7 minutes"), weight ("squat with a barbell as heavy as I am"), or simple completion ("finish a 5k"). This will shape your training in a way that makes you more fit, while also restructuring your body.
If you absolutely must have a science-y number to track, the Body Shape Index, which uses BMI but isn't directly correlated to it, and seems to be a better predictor of one's risk of death. Keep in mind that while it takes belly fat into account, it still does not keep track of muscle or actual markers of physical health, like mobility, strength, inflammation, diabetic state, or cardiovascular disease.
Body Shape Index= Waist Circumference/[(BMI^(2/3))*(height^(1/2))]