The Real Madrid and Spain goalkeeper has come in for criticism after a mistake in the Champions League final against Atletico Madrid was followed up with a disastrous World Cup for Spain.
Speaking ahead of Tuesday’s Uefa Super Cup tie against Sevilla in Cardiff, the 33-year-old said he was confident of a successful season and had analysed his recent mistakes.
"I haven't been at my best in the last few games for Real Madrid and Spain, but I have analysed and learned from them," he told reporters.
"I have been through worse moments in my career. You go through good moments and bad moments. Everything is temporary. I have not been at the level I was when maybe people became spoiled.
"You have to grin and bear it and face up to situations like this. I have always done so and I am not going to hide now.
"I understand that when you play for Real Madrid you are always being watched and your name is talked about when things are good and when they are bad. Luckily, in my case it has almost always been when things are good.
"I don't feel targeted. The club has treated me very well, I have no complaints. I want to push myself even harder than last year."
Casillas said Carlo Ancelotti’s side were determined to continue picking up silverware after winning the Champions League and Copa del Rey last season, starting with the battle against Europa League winners Sevilla.
He continued: "I'm excited about getting back to winning. We can't live on the memory of what we did a few months ago. We have to win the Super Cup to gain confidence and then go for the Spanish Super Cup as well.
"This is an important game for Madrid after the prize of winning la Decima. It is a day to be enjoyed and to win. At Real Madrid we are obliged to win and to go for the trophy."
Madrid have signed Keylor Navas from Levante this summer to provide competition to Casillas, while Diego Lopez is on the brink of leaving to join AC Milan.