Morse, who turned 26 on March 22, hit .444 in nine games with Seattle last year and has a career .302 average in 102 games in the Majors.
"Making the team is just the beginning," Morse said. "Now you've got to produce. Now this is where it counts. Spring Training stats aren't on the back of your bubble-gum card.
"I just want to have fun -- see how long I can have fun for. I'm having so much fun in what I was doing. I thought I was bringing a lot to the table this spring. In my mind, I was getting ready for the season. So when [McLaren] told me I had made the team, it was already in my head that I thought I was on the team.
"In years past, I pressed, pressed, pressed so hard. This spring, it was just go out and really show them what you've got. Just have fun and play baseball like we did when we were all kids."
Jimerson, 28, made an Opening Day roster for the first time since starting his pro career in 2001 with the Astros.
"It was not like I imagined it to be," Jimerson said of when he was told he was on the team. "I'm glad I made the team. I definitely feel for guys that got different news, because I've been there four times.
"It's a big pat on the back. There have been a lot of people who counted me out -- not around this organization. I think those who doubted if I'd be back in the Major Leagues or even having a chance to be on a roster, I think this is a pat on the back. Those who have helped me over the years, this is a big pat on the back for them, too.
"I'm easily motivated by naysayers. I guess they'll still be around, so I still have some fuel for the season."
Jimerson has appeared in 29 Major League games and has four hits in eight at-bats, while he has played in 649 Minor League games. When the Mariners opted to keep an extra bench player and go with an 11-man pitching staff, it opened up a spot for Jimerson.
"Competition for me has always been personal," Jimerson said. "Who you are competing against is not important to me. If I can take care of myself, that's my competition. Competition is to stay on top of my game. After the game, it was never like, 'Oh my gosh, Mike had four hits today. I may not hang out with him or talk to him because that's my competition.' That's just not my style.