Martino is coming under increasing pressure over Barca's perceived poor form and fielded a host of probing questions as he met media to preview Wednesday's visit of Manchester City.
The Spanish champions were beaten 1-0 by relegation battlers Valladolid last weekend to slip to third in the Primera Division, four points behind leaders Real Madrid.
Their position seems healthy, especially as they are also through to the Copa del Rey final and will reach the Champions League quarter-finals if they finish off City, having beaten them 2-0 last month.
But that has not stopped speculation over his future at the Nou Camp, where expectations are lofty after three European triumphs in the past eight years.
Martino, who took charge last summer, told reporters: "I always stay strong especially thinking of everything that lies ahead.
"I won't forget about the league, we have a cup final and we can reach the Champions League quarter-finals.
"If I wasn't upbeat I would change jobs.
"This team is brave and is motivated. We have not been consistent enough, but there's not a problem with motivation or performance.
"Barcelona have good enough players to aspire, every season, to win titles. These players will turn things around.
"They know what's expected, so I don't need extra motivation.
"We did make lots of mistakes against Valladolid but that isn't normal in this team."
Martino's men are firm favourites to move into the last eight having dominated the first leg of their last-16 tie against City three weeks ago.
The Catalan giants dominated possession and broke through with a Lionel Messi penalty after the Argentina star was brought down by compatriot Martin Demichelis, who was sent off.
City did create some good chances on the counter-attack but failed to take them and Barca's superiority eventually yielded a deserved second goal through Dani Alves.
Martino knows his side hold a strong advantage but will not take anything for granted against a City side reeling themselves after a shock loss to Wigan in the FA Cup last weekend.
He said: "We played a very good match against Manchester City.
"I don't see why we can't do the same tomorrow and I am sure we will play well.
"We have to separate the league from the Champions League and we are at an advantage.
"But I think the way we could risk the result is thinking that we won 2-0 over there.
"The best thing is to think it's still 0-0 to try to win the match.
"We can't think about speculating with the result simply because we're in the lead.
"I think City will make changes to the team. (Sergio) Aguero is very dangerous but they have many other players who are just as worrying."
City's top scorer Aguero missed the first leg through injury but is now back in action.
Defender Javier Mascherano, the former Liverpool midfielder, believes Barca should take a similar approach to the first leg.
He said: "(We should) keep possession, don't give them any chance to make counter-attack, don't give them any chance to play in big spaces.
"The right way to do it is to try to get the ball in the majority of the game.
"They have the team to fight (for) titles in Europe, they have a lot of great players - but hopefully not tomorrow."