The so-called 'farmer's walk' is an old way to build stamina, strength, endurance, etc. and has innumerable ways to be performed. If you have a yoke, you can place that on your shoulders and attach buckets of sand, water, maple tree sap(as did when a kid on the farm during sugaring time) and so forth, and walk around and do sort of squats by lowering your buckets to the ground from time to time. Other ways, include walking, as many strongmen did in the old days, with barbells on your shoulders or carrying heavy dumbbells in your hands(to strengthen your grip) and even suitcases,etc. or buckets,etc. You can also carry barbells or heavy sacks on your chest with hands like a press,etc. or on your shoulder(s), varying the shoulder. You clan place heavy planks, logs, etc. on your shoulders and so forth. You can walk with arms extended overhead with a barbell or other heavy thing and walk around. You just have to use your imagination and take care not to overdue or injure yourself or to show off. Walking in circles, straight lines, or going backwards and forwards,etc. will also be ways to do all this. Or walking uphill or downhill or up inclines,etc. Well, I guess you get the idea. Walking in snow or on sand dunes and on beaches,etc. is a way some do to improve things. Just working a modern gym has its drawbacks for all this, however.