NAIROBI - Barack Obama told Kenyans on Sunday on his first presidential trip to his father's homeland that there was "no limit to what you can achieve" but said they had to deepen democracy, tackle corruption and end exclusion based on gender or ethnicity.After political talks on Saturday with President Uhuru Kenyatta on security and business, his speech to a packed sports hall in Nairobi struck a personal note, talking of his own experience and Kenya's in the five decades since independence."I'm here as president of a country that sees Kenya as an important partner. I'm here as a friend who wants Kenya to succeed," he said, after being introduced by his sister Auma Obama to a crowd who had secured tickets to attend.To a mixture of applause and laughter, he described being picked up at the airport on his first visit to Kenya in the 1980s by his sister in an old VW Beetle that often broke down. This time, he arrived on Air Force One and traveled in the president's armored car nicknamed "the Beast.""When it comes to the people of Kenya, particularly the youth, I believe there is no limit to what you can achieve," he said, but he told Kenyans building their nation and the economy required personal effort and responsibility.