Chest discomfort. To seek an advice?

Dear DR, I hope this message finds you well. I am writing to seek an advice regarding some health concerns i have been experiencing. I am a 20 year old male with a height of 5.3feet and a weight of 68kg. I have recently noticed that I experience light chest heaviness after lifting heavy objects. Additionally, i have observed a sudden rise in my heart rate when i change my posture, such as when i stand up from a sitting position. I am also physically inactive and have not been following a regular exercise routine. These symptoms have been concerning me, and i would appreciate your guidance on what steps i should take next. I am particularly interested in understanding if these symptoms could be related to any underlying health conditions and what lifestyle i can make to improve my health.