A strong veteran, having trained for tens of years, can fall to a weakling in a moment of laxness. That's what the martial arts world is.

He forged the steel into a sword.

The men are getting into shape riding bicycles.

Build up your body while young.

I end up unconsciously trying to get fit as summer draws near.

To be an interesting person you have to feed and exercise your mind.

Exercise trains the muscles.

To begin with, you must build up your body.

The fighter toughened up for the bout.

If he had trained himself harder at that time, he would be healthier now.

It's by smithing that one becomes a blacksmith.

When men go to the gym it seems they really work their biceps.

To work your pectoral muscles try doing thirty push-ups.

I must brush up my English.

Tom spent many hours using the language website, tatoeba.org, to improve his English.

I like working out.

First you have to build up your vocabulary.