But can lift heavy objects

Have managed a few runs & a few swims. But at some point, when trying to get a bit 'fitter', one must lift a heavy object.

Now I'm not declaring these are heavy but if you hold them up for a period of time they do start to increase the effort needed to continue on. And if they're above your head...the risks also go up just saying is all.

Shoulders, back, delts, pecks, chest, core, quads, calves & hami's all feel the burn