It's no excuse, it's a convincement. There are far more important things in life than doing weight lifting etc. If you ask people who are about to die what things they regret, none of them will say 'Oh I feel so sry for myself that I didn't do any exercises.' but stuff like 'I should've spent more time with my family'. As long as your diet is alright your physical appearance will be too. However, if you have a super-body but you don't enjoy your life all you see is darkness. I know people who are close to me that are going through hell even though they are great in shape. But they couldn't care less about what BMI they have.