Jennifer Lopez's boyfriend thinks she runs like she's 25.

The 48-year-old actress has always been praised for her youthful looks and tight physique, but even her beau Alex Rodriguez, whom she's been dating for over a year, was surprised when she ran across to him at lightning speed last week.

Speaking to Emmy magazine, she said: ''The other day, Alex was across the lawn, and I brought him something, and then I ran away.

''And he said: 'You run like you're 25 years old.' I haven't stopped that pace, so I'm still at that pace, I guess. When things start aching more, it'll be different.''

However, the brunette beauty - who has 10-year-old twins Max and Emme with her ex-husband Marc Anthony - understands that eventually time will catch up with her.

She explained: ''Listen, at some point, I'm going to age. They'll say, 'She looks old!' But, right now, I'm holding it together. I just take it day by day, because it's so much stuff, and I try not to worry about too much.''

It hasn't been easy for Jennifer in the public eye as she recently admitted that in the early days of her career she was told to ''lose a few pounds'', but refused to take anyone's advice because she was proud of the way she looked.

She said: ''They didn't bother me at all. But I got a lot of flak for it from people in the industry. They'd say, 'You should lose a few pounds,' or 'You should do this or do that.' It finally got to the point that I was like, 'This is who I am. I'm shaped like this.' Everybody I grew up with looked like that, and they were all beautiful to me. I didn't see anything wrong with it. I still don't!''