The most important thing before you start a new exercise; consult a doctor and/or other medical professional. Ask he/she to give you full medical to see whether there are any problems that could be aspirated by you starting an exercise program.
Get your feet and ankles checked out by podiatrist.
Calculating you BMI
BMI = Mass(kg)/ (Height(cm)x2)
BMI = Mass(lbs)/ (Height(cm)x2)*703
BMI gives you a rough guide in how fit you are
BMI range – kg/m2
Very severely underweight
less than 15
from 15.0 to 16.0
from 16.0 to 18.5
Normal (healthy weight)
from 18.5 to 25
from 25 to 30
Obese Class I (Moderately obese)
from 30 to 35
Obese Class II (Severely obese)
from 35 to 40
Obese Class III (Very severely obese)
The only people that this does not apply is professional athletes. An example of these American Footballers or Gridiron players with very low body fat but extremely high muscle mass.