Don't waste your money on fancy gadgets. Do some old fashion training, such as:
Start competing in Track & Field events.
Start training for Iron Man competitions.
Take some gymnastics.
Train for long distance swims in the ocean (not a pool).
Find a course on Drown Proofing. How to stay afloat for days. As taught to SEALS.
http://en.wikipedia.org/wiki/Drownproofing
Army special forces such as SAS or SEALS emphasize ENDURANCE over brute strength. The candidates who have the highest chance of completing SEAL or SAS training are the best runners first, and swimmers second.
But emphasize Endurance training over weight training or strength base training.