Adult Americans average more than an hour of exercise daily, but most think they fail to exercise enough, said a survey released Monday.

Parents magazine said the survey of 1,006 adults found 43 percent of the respondents felt they got enough exercise, but 56 percent felt they exercised too little.Americans average 8.7 hours of exercise weekly, the survey said.

The most popular form of exercise is walking rapidly, cited by 64 percent of the respondents, the survey said.

Another 44 percent said they rode a bicycle, 39 percent said swimming was their favorite exercise and 32 percent said they played a sport, the survey said.

Asked if they were happy with their weight, 47 percent of the respondents said they were, the survey said.

Another 41 percent said they were somewhat overweight, 5 percent said they were "appreciably overweight" and 6 percent said they were too thin, it said.

Of the respondents who are parents, 77 percent said their children exercised enough and averaged almost two hours of daily exercise, the survey said.

Fifty-one percent of the children participated in team sports, 33 percent rode a bicycle and 24 percent ran, jogged or participated in track sports, it said.

The favorite family exercise is hiking and walking, which 39 percent of the respondents with families reported doing. Another 23 percent of the families said they swim together and 22 percent rode bicycles, it said.

Half the respondents with families said they exercise together, it said.

The random telephone survey of 1,006 adults over age 18 was conducted in September and October 1987 for the magazine by Kane, Parsons & Associates. The margin of error was plus or minus 3 percent.