Easter faith is a gift from God; we should pray for the grace but cannot reason or talk ourselves into it. We can, however, try to understand it and to deepen our recognition of what it means for our daily lives. And with so much riding on Jesus' resurrection, it's only reasonable to ask, "What happened?"
We can imagine two extreme responses to this question. On the one hand, that Jesus' rising was a bodily resuscitation—as if he woke up and had to go to the bathroom—and on the other, that his rising was only in the hearts and hopes of disappointed disciples. Each one is false—to the New Testament witness—but they help us to locate what did happen in between them.
So, the Resurrection was not the kind of resuscitation that the disciples had experienced when Jesus raised Lazarus from the dead (Jn 11:1-44), or the daughter of Jairus (Mk 5:21-43) or the son of the widow of Nain (Lk 7:11-17). These three would live a while and then have to die again. Rather, the body-person of the risen Christ was transformed. Unlike a mortal body, he could pass through walls (Jn 20:19); he could walk along with and then "vanish" from two disciples on the road to Emmaus (Lk 24:31). By all accounts, "he appeared in another form" (Mk 16:12). A whole throng of disciples, having seen him bodily "alive," then witnessed him ascending from their midst "into heaven" (see Acts 1:6-12 and Lk 24:50-53).
On the other hand, Jesus' resurrection was not just wishful thinking on the part of disciples. To begin with, they clearly were not expecting it; those two disciples on the Emmaus road spent a whole day with him before recognizing who he was. Others upon his appearance were "startled and terrified and thought that they were seeing a ghost" (Lk 24:37). If this were a made-up story, they surely would have represented themselves better.
Then the disciples were transformed by their conviction that God had raised him up, many giving their lives in witness to this truth; such commitment is impossible from a conspiracy of fond hopes. The disciples knew that his resurrection was "real" because Jesus had shown them the wounds in his body—even inviting Thomas to touch them (Jn 20:24-29). He had asked them for food and eaten it (Lk 24:36-43); why, he'd even invited them to breakfast (Jn 21:12).
So, what did happen, between these two wrong responses? Those first disciples recognized Christ's resurrection as very real, though they could not fully name his new mode of spiritual embodiment; it was a new phenomenon to their experience—of "another world," as it were, within the life and power of God. Nor can we describe it, never having known as much in our experience. Yet we are invited to join in the rock-solid conviction of those first witnesses that Jesus "was raised on the third day" (1 Cor 15:4).
If we can, by God's grace, then all should be changed, changed utterly. Why, we even confess in the Apostles Creed that we fully expect "the resurrection of the body" for ourselves at the end of time. And it only seems reasonable to wonder which body will rise; I certainly want my 21-year-old one—with all my hair and vital functions (Source: americancatholic.org.).