"Grief goes with you every day, whatever you're doing, when there's great moments, when there's hard moments," the Glee actress said.
The 27-year-old, whose co-star and boyfriend Cory died of a heroin and alcohol overdose in July, spoke about returning to the set of the hit musical TV show soon after his death.
"I'd rather, for me, be at work with the people that I love that are going through the same thing. And it obviously has its own triggers. But at the end of the day, I feel so safe there.
"Going to work is no harder than being at home and being in the house and opening up a closet and seeing a pair of shoes."
The American actress remains optimistic about her future.
"I think at a certain point you can choose to sort of fall from this, or you can choose to rise. And that's what I'm just trying to do," she said in an interview airing on Thursday on The Ellen DeGeneres Show.
"I know that that's what he would have wanted, to just do my best and to hopefully make something positive for where I go in the rest of my life."
The New York-born star has sought advice from her mother about dealing with her grief.
"My mom has experienced a lot of loss in her life, and she told me at one point that there is an empowerment that comes with grief.
"At some point you find it. It's very hard, but you will find it."
The Ellen DeGeneres Show will hold a special place in Lea's heart because it's where Cory, who died alone in a Vancouver hotel room, revealed that they were together.
"It's one of my favourite memories," Lea said. "I remember when he came home that night, he kind of puffed out his chest, and he was like, 'I talked about you on Ellen today,' and I was so happy.
"He's such a private person, and I literally lived every day of my life feeling like the luckiest girl in the whole world."