Arnold Schwarzenegger says his 13-year-old son Christopher will soon be back \"at full speed\" after a surfing accident last week left him hospitalized in intensive care. The former California governor and movie star -- who is being divorced by his wife Maria Shriver after he admitted to fathering a child by their housekeeper -- thanked well-wishers who voiced support for the boy\'s recovery. \"Thanks for all your support for Christopher. It means a lot to me & to him,\" said Schwarzenegger, who released a joint statement with Shriver on Friday talking about \"our son Christopher.\" \"He\'s doing much better & we\'ll have him back at full speed soon,\" he said on his Twitter feed. The teenager spent last week in intensive care after suffering broken bones and a collapsed lung in the boogie-boarding accident in Malibu the weekend before last, according to media reports. Shriver filed for divorce three weeks ago citing \"irreconcilable differences\" with her husband, whom she married in 1986, following his admission in May that he fathered a child with the couple\'s housekeeper. In filings to the Los Angeles Superior Court last week, Schwarzenegger said he would refuse financial support for Shriver, while seeking joint custody of their two minor children, Patrick and Christopher. Shriver is a member of the storied Kennedy political clan, and jointly she and Schwarzenegger are reported to be worth $400 million. The Austrian-born former bodybuilder, a liberal Republican, left office in January, and started to return to show business, with plans for a \"Governator\" comic book and animated TV show. But he put his comeback on hold in May, telling his agents that \"all his motion picture projects currently underway or being negotiated (should) stop planning until further notice.\"