Use your time at the Gym wisely so you earn as many attribute points as possible while you are there. If fractions of the coloured icons appear instead of the full thing it is to indcate you need to change exercise. You will make the best gains if you rotate between exercises. Listed below are the different pieces of equipment in the gym and what they will train for you.
Speed Bag:
Agility
Heavy Bag:
All three Attributes
Treadmill:
Stamina
Squat Rack:
Strength and Stamina
Dip Bars:
Strength
Bench Press:
Strength
Sledgehammer:
All three Attributes
Jump Rope:
Agility and Stamina