Getting fit? Help please xD

[Swat Runs Train]

That's all good until you get a heart attack from working that muscle too hard.

If you've been sitting around for the past few years chewing down McDonalds fries and hamburgers I doubt that would be good to strain yourself to the limit right away. People don't run marathons in a day, especially if you're older. You push yourself to a higher limit of course, but not until you can't go any longer. And for the first time in a while, I wouldn't suggest taking it to the highest level right away.

There's a difference between pushing yourself and being a fool lol, you go until you're tired and feeling the endorphins that always come with a solid effort, not about to collapse and die.