The Trotters missed the chance to move out of the bottom three of the Barclays Premier League on Wednesday night as they were beaten 4-1 in their game in hand by Tottenham at the Reebok Stadium, and they now trail 17th-placed QPR only on goal difference.
They now host mid-table West Brom on Sunday before travelling to Stoke on the final day of the season, and Coyle said: "I have said to the players, as young a group as they are, 'You have got to stand up and be counted and show your character in adversity, and you have got to come through'."
A point against Spurs would have lifted Bolton above QPR but they missed that opportunity after conceding three goals in the space of nine second-half minutes.
Coyle added: "That is what I always say, and the real stars always shine brighter. That is when you have to stand up and be counted and that is what Sunday brings.
"You have to be ready to show that you are brave, and I don't mean charging about the field. I am talking about being in possession of the ball, trusting yourself.
"We know we have enough quality in that squad to go and get two results but the first one, being Sunday, is a massive game - our biggest game of the season and we have to be ready for it."
Against Spurs, Nigel Reo-Coker had cancelled out Luka Modric's stunning opener with a well-worked equaliser soon after the break and Bolton had been pressing for a second.
But a swift Spurs counter-attack set up Rafael van der Vaart and two more quickfire raids saw Emmanuel Adebayor leave with a double.
Coyle was left disappointed, but said: "We have confidence, we have been on a good run. It is about regrouping and taking it smack in the teeth. It is not a great feeling but I have been in football long enough to have experienced a lot of highs and lows."
Source: PA
Source: PA