So I was out of the gym for like 6 weeks or so (maybe a little longer). I'm still overweight and just not happy with myself, so yesterday I started back in the gym. Did some powerwalking/running for 30 mins - then did strength training for about 30 mins. Took a shower and left feeling GREAT, and hungry. took a whey shake and drank it. Had some Tuna as well. By the end of the night my chest felt kinda tight, but I worked my chest so I thought nothign of it. Today i went to work then went to the gym after work. Did 30 mins on the treadmill again and then worked out biceps and back. Had a shake and went home. Ate some tuna again tonite. (I like tuna ) Now my chest feels like its going to explode, like it's not muscle soreness, I know what that feels like, It feels like my heart is working really hard, I'm kinda worried about it. Like I'm not short of breath or anything, I feel pretty ok otherwise, but I just am the type that worries, so I'm wondering if I am being to hard on my heart? For reference, I'm 6'1 and like 255, My bodyfat is likely high, I don't know how high tho. I'm average build, on the fatter side tho. So what do you guys think? overworking myself or is it just my body being shocked because of all the activity its doing?