The Slovenia international has started this season with four goals and three assists in seven competitive matches.
"Everything is needed. In the past, it was enough to excel in one aspect," says Sesko to Gazzetta dello Sport.
"Now you have to be complete if you want to compete at the highest levels. You have to think fast too. Football is so fast that you have to read what is going to happen and use your body wisely."
Sesko has been linked with Arsenal, Barcelona and Manchester United this season.
"I will not comment on transfer speculation," the 21-year-old said.
"I am happy in Leipzig, and for this reason I recently extended my contract. I want to do big things here, and Leipzig wants to get better. I want to accompany the team on this exciting path."