Jacobs had terrible timing with the tweet Thursday afternoon, considering his boss — San Francisco coach Jim Harbaugh — was hospitalized for what the team called a “minor procedure” because of an irregular heartbeat.

In the locker room at Santa Clara team headquarters soon after his post, Jacobs said people shouldn’t “assume” his remarks were football-related, then followed up with more tweets — including one reading “football is not my life, people” and another saying, “Have you ever been in a spot and you wonder why are you there.” Later, he posted that his tweets referred to his brother’s boss, who makes “him feel like he is the best thing since slice bread but when the budget is shot he is the first one get laid off, same with two other people I know.”

Jacobs, who missed time with a left knee injury early in the year but says he is now fully healthy, has been active only once all season but never played for the NFC West-leading 49ers (6-2-1). He took the field for a play Oct. 18 against Seattle, then got called off.

Jacobs certainly seems frustrated, even if he doesn’t always say it.

When asked if he has allowed himself to think beyond this season, Jacobs said: “Have I allowed myself to think about the future? Nah, because the future is not here, current, what’s happening now. … I’m pushing hard every day.”

In a strange twist later Thursday, rookie running back LaMichael James retweeted Jacobs’ initial post with the “hate your boss” reference and being happy at work. James, a second-round draft pick out of Oregon, hasn’t played at all this year, either.

Jacobs has said several times that any questions about his lack of playing time should be taken straight to Harbaugh.

“I feel good. I’m coming out and working hard every day,” Jacobs said. “I feel really good right now, man, and that’s about all I can elaborate on. I’ve been saying that for a while. It’s not about that. You guys have to talk to coach Harbaugh. He’ll tell you whatever you want to know. … It’s not about me.”

Jacobs signed a one-year deal with San Francisco in late March after spending seven seasons with the New York Giants. He won two Super Bowls and beat the 49ers 20-17 in overtime of the NFC championship game at Candlestick Park on Jan. 22.

In June, Jacobs received a letter from a 6-year-old Giants fan named Joseph that included $3.36 in cash from the boy’s piggy bank — the child’s contribution to try to keep Jacobs in New York with the reigning Super Bowl champions. The boy’s mother, Julie Armento, wrote that she explained to her son that the Giants didn’t have enough money to bring Jacobs back on a new contract, thus prompting her son’s adorable gesture.

Jacobs then connected with Joe before the season when he returned home to New Jersey.

The 30-year-old Jacobs ran for 571 yards and seven touchdowns last season as a backup to Ahmad Bradshaw. He is the fourth-leading rusher in franchise history with 4,849 yards, but saw his role diminish with the emergence of Bradshaw.

Now, he is behind three-time Pro Bowler Frank Gore and Kendall Hunter among others. Jacobs knew full well he was joining a busy backfield.

“I come to work every day, I work hard, and that’s just about all I can do,” Jacobs said. “That’s it.”