Dear Sir /Ma'm
Thanks for writing to HC magic
1. There is no fixed optimal heart rate
for an individual. if your routine HR is 94 bpm and you are comfortable with it, then i would tend to agree with your GP's observation.
2. If your heart rate goes up too quickly during exercise, my first inference is that your body is not habitual of doing exercise. Second possibility can be that you have a diseased heart but in that case you would feel too short of breath along with increase in heart rate and it will take time for you to get your breath back, in that scenario you may have chest pain
or feeling of being drowned in water also. (in this case you must see your doctor on priority).
In both the cases pushing harder is not advisable.
if you did not experience any troublesome symptoms, you must build up your stamina slowly and then see the results. Go for exercising but start from level 1 of difficulty , do not straightaway go for level 4. gradually increase your level. if anytime you feel unusual discomfort/undue shortness of breath/ chest pain, please consult your doctor.
i hope i cleared your doubt.