Traveon Beck was feeling optimistic. For two months, the former Cal defensive back had awoken at 5 a.m. to slog through rigorous workouts, adding 15 pounds of muscle and improving his 40-yard dash time.

After he didn’t land an invite to the NFL scouting combine, Beck — fresh off an injury-marred senior season — knew that the Bears’ March 20 pro day would be his best chance to convince a team to draft him. Then, just a few days before scouts were scheduled to arrive on campus, Beck learned that the showcase had been canceled to limit the spread of the coronavirus.

“I was a lot more explosive and a lot faster, so I was really looking forward to showing off my new body,” said Beck, who isn’t listed among CBS Sports’ top 500 prospects for the April 23-25 draft. “When I found out pro day wasn’t happening, it felt like all that preparation went out the window.”

NFL rosters are loaded with little-known college players who made an impression at one of several annual showcases. For those not included among the 337 prospects at February’s combine in Indianapolis, pro days — events held at campuses throughout the country that feature scouts with stopwatches and notebooks — offered an opportunity to ease teams’ concerns and realize a longtime goal.

An impressive time in the three-cone drill or 40-yard dash could be enough for a fringe player to surface on franchises’ radars. That’s what happened with 49ers running back Raheem Mostert, who, five years before he rushed for 220 yards and four touchdowns in January’s NFC Championship Game, ran the 40 in 4.32 seconds at Purdue’s pro day.

Though he’d rushed for only 759 yards over his four years with the Boilermakers, Mostert signed with the Eagles as an undrafted free agent. It was the entryway he needed for an NFL career that recently culminated in a Super Bowl start.

“Obviously everyone would like to get drafted, but all we really want is a chance to show we belong at that level,” said former San Jose State quarterback Josh Love, who has been in contact with several NFL teams despite not getting to participate in the combine or the Spartans’ pro day. “Whether I’m drafted or undrafted, I’m going to have the same attitude. I’m going to compete.”

This mentality is a requirement for professional football’s striving class. Outside of the fortunate few widely projected to go in the draft’s first couple of rounds, NFL hopefuls must do whatever they can to prove they’re worthy of a contract.

Three weeks ago, when pro days across the U.S. were canceled, fringe prospects got creative. Former Stanford running back Cameron Scarlett recorded a makeshift pro day with a couple other players at California Strength, a training facility in San Ramon. The seven-minute video, which has been sent to numerous NFL teams, shows him doing all the events in which he would have participated at the Cardinal’s pro day.

“Generally, we only trust what we see with our own eyes,” said an NFC scout, who spoke under the condition of anonymity because he’s not authorized to talk on the subject. “Video of a pro day is great and all, but we’d far prefer to see them in person. We want to be able to time things ourselves.”

This is why Beck and Love opted not to do their own pro days. Beck has sent his Cal highlights to several teams who expressed interest in him after the Hula Bowl, the college All-Star game in Honolulu. Love, who threw for 3,923 yards and 22 touchdowns as a senior at San Jose State, has had FaceTime interviews with multiple teams in recent weeks.

Other than talking to executives and working out at home, NFL hopefuls must sit and wait for the draft to unfold. Even the most upbeat of prospects can’t help wondering: What if those years of sacrifice were for nothing? What will I do if I don’t land with a team?

Scarlett, who didn’t receive a combine invite despite leading Stanford with 840 rushing yards as a fifth-year senior, reaches out to his older brother, Brennan, whenever doubts begin to take their toll. Just four years ago, Cameron watched in their Portland, Ore., living room as Brennan — an All-Pac-12 defensive end for the Cardinal — scoured NFL rosters after going undrafted.

Convinced that he could make the Texans, he told his agent that he wanted to sign a free-agent deal with Houston. Last season, Brennan started 10 games for the Texans, totaling 31 solo tackles and 3 ½ sacks for a team that reached the second round of the playoffs.

“I’ve seen so many guys close to me who’ve gone undrafted, then made it work in the long run,” Cameron said. “I see no reason why, even if I go undrafted, I can’t do the same.”

Connor Letourneau is a San Francisco Chronicle staff writer. Email: cletourneau@sfchronicle.com Twitter: @Con_Chron