The former England captain drew some flak in the U.S. media for training with English Premier League club Tottenham Hotspur and missing the formal start of pre-season with the Major League Soccer's Galaxy.
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"I think at this stage in my career, especially after the injury that I had, I realised that it was more important for me to train than to sit on a beach," the 35-year-old told reporters after returning to training with the Galaxy on Thursday.
"It was just important for my fitness and for my level that I continued there and come back fitter than I obviously was last season," said Beckham, who missed most of last year's campaign due to an Achilles tendon injury.
Spurs manager Harry Redknapp had tried to secure Beckham on a loan deal which would have allowed him to play for the North London club.
"If obviously there was an option to play then I was going to take it. But without doubt, a hundred percent, I wanted to go somewhere and train and not take the three months and just sit around doing nothing," he added.
"My main objective was to get fit for the Galaxy and for the MLS season. That was my main objective. My main objective wasn't to play for a premiership team.
"I was thankful to Spurs and to Harry for the way they looked after me. I think it was frustrating for Harry because he's already said that he would have liked to have signed me for the time," said the former Manchester United and Real Madrid midfielder.
Beckham denied that a loan deal with Spurs would have meant he would have missed games in MLS.
"Even if I had been on loan, even if I had played the games, this is the time I was always coming back. You know that was agreed. You know nothing was going to change that," he said.
Beckham has been invited to the wedding between Britain's Prince William and Kate Middleton on April 29 but he said he did not know if he would attend. The Galaxy are due to play in Dallas on May 1.
The Galaxy open the MLS season at the Seattle Sounders on March 15.
