Hi!
You don't have to be embarrassed at all. The fact that you were never into any kind of physical activity could have been different. But you should be proud of yourself that you have started with it now. Better late than never.
Low stamina is also a result of low haemoglobin, since it is responsible for carrying oxygen to your cells.
Considering your health factor, I would suggest you to focus on your diet. Needless to say you're already doing your bit with working out. These are some tips, hope you find them helpful.
1. See to it that you are well hydrated all the time.
2. About 30 minutes before workout, have a fruit or some dates. These will provide you with adequate energy.
3. Consume iron rich foods such as garden cress seeds - you can have them in the form of laddoos or kheer. Have green leafy vegetables, dates more frequently. Rajgeera laddoos are also good. You can have those with milk.
4. Make sure you have the juice of one lemon daily. Or you can have aamla or any citrus fruit instead.
About your workout, do not worry. Just decide to stretch your limit a bit everyday. You're doing great!
Next Steps
Book a consultation on Practo for a personalized diet plan for your goal.