Where in your chest, Mr Accurate Representation of Patient with nonspecific Description of Symptoms?
If it’s with every deep breath that might be a big deal I think, but you don’t sound that concerned about it, so the sensation may not be too severe (or in a bad place). Since your concern may appear minor I will guess it’s only sporadic and/or perceived as not originating from a bad place.
If it’s minor or sporadic I would guess your body may be telling you about developing atherosclerotic disease. Thank you for no information about your physique or diet Mr nonspecific. That’s really OK though - even in RL - how often do we provide accurate histories.
If it’s major pain or consistent, I would guess musculo / respiratory / vascular
Health really is important I need to start working out again