Maybe there is a problem with your lifestyle? Otherwise, you might have a medical condition, you should see a doctor. 30 is young. Walking a few kilometers is something you should be able and do daily, or at least a few times a week. I work mostly with people in their 50 and pretty much all of them are in great shape. Also, US seems to have an overweight problem that affect people on many aspect of their health. It can be hard (tell me about it) but changing food habit can have major impact.
Maybe there is a problem with your lifestyle? Otherwise, you might have a medical condition, you should see a doctor. 30 is young. Walking a few kilometers is something you should be able and do daily, or at least a few times a week. I work mostly with people in their 50 and pretty much all of them are in great shape. Also, US seems to have an overweight problem that affect people on many aspect of their health. It can be hard (tell me about it) but changing food habit can have major impact.