The former Hoops and Scotland player was speaking a day after it was confirmed that Norwegian midfielder Kristoffer Ajer will join the Parkhead club in June on a four-year deal following a January trial.
The 17-year-old will provide added competition in an area which looks particularly over-stocked already, with new additions Scott Allan and Ryan Christie struggling for game time and Patrick Roberts, on loan from Manchester City, yet to make an appearance.
Ahead of the visit of Inverness on Saturday, Collins was asked how close the Ladbrokes Premiership leaders, who have first-team regulars Charlie Mulgrew and James Forrest out of contract this year, were to having too many players.
“Come the end of the season there will be players who will move out,” he said.
“But at this moment in time it is a big squad, everyone is fighting to be in the squad and that’s a good problem to have for the manager, myself and the coaching team.
“It is always the challenge. Better having too many good players than not enough.
“You can’t keep them completely happy. I would be telling a lie, everybody would be telling a lie if they think everybody is happy at a football club.
“You have 11 starters who are very happy, the substitutes who are a little bit unhappy, and you have ones who are sitting in the stand who aren’t happy.
“That is the same the world over, every club in the world.
“It is difficult for players when you are not playing, we understand that.
“They are human beings as well as footballers but you have to make sure that they take that disappointment in the right way and stay focused.
“The most important thing is that the players realise that to get into the team they have to train well, stay focused and remain positive.”
Asked about Ajer, back with Start in his homeland, Collins said: “Young Kristofffer did very well last month, 17-years-old, he fitted in very well on the training pitch and showed lots of composure, calm on the ball - a good football player.”