3:10 My aim is to know him, to experience the power of his resurrection, to share in his sufferings, and to be like him in his death, 3:11 and so, somehow, to attain to the resurrection from the dead.

The word for ‘resurrection’ – exanastasis – is used only here in the NT (the usual word being anastasis).  But Paul’s meaning is detected not by the use of this word but (according to F.F. Bruce) by the context.  Paul had no doubt about his resurrection on the last day (1 Cor 6:14; 2 Cor 4:14).  His desire to be conformed to Christ’s death and his hope to attain the resurrection from the dead are both to be construed in the same sense of his language in 2 Cor 4:10f:

‘Paul endured many sufferings by reason of his apostolic service, and they might well have got him down, had he not learned to accept them as a sharing in the sufferings of Christ, so that the power of that risen life might be his present experience too.’ (Answers To Questions, p109f)

‘Paul recognizes that the believer’s perseverance depends on the will and the working of the sovereign God (Php 1:6; 2:13; 3:12-14,21; cf. Heb 6:3).’ (New Geneva)

‘What is this language “somehow, to attain”? That is the language of humility and of hope. Paul knew he had not yet attained the resurrection, for he had not yet died. His physical resurrection was still a future hope. It is not that he is unsure of it, for Christ is already risen so the eventual resurrection is sure. The point he is making is that he is not there yet. He is still “pressing on.”’ (HSB)

Ralph Martin agrees:

‘The qualification and so, somehow (ei pōs, suggesting a clause in which the attainment of a purpose is not altogether within the subject’s power; so Bruce) reflects the same uncertainty of his immediate future which was noted in Phil 1:22–23, i.e. relates to the immediate prospect of his trial and its issue, which hangs in the balance at the time of writing. He would cherish the prospect of death as a decisive step nearer the resurrection, but acknowledges that it may be God’s will for him to remain alive for the Philippians’ sakes. There is no lack of certainty about his salvation and ultimate bliss. He knows that nothing can separate him from the love of God (Rom. 8:38–39): what is in doubt is the way he will go home to God, whether by martyrdom or not.’ (TNTC)

Paul is confident of the outcome, but equally sure that it does not come without striving on his part:

‘When Paul, with reference to this out-resurrection out of the dead writes, “If only I may attain,” he is not expressing distrust in the power or love of God nor doubt as to his own salvation. Paul often rejoices in assurance of salvation (Rom. 6:5, 8; 7:25; 8:16, 17, 35–39. In this assurance he was strengthened as the years went by (1 Tim. 1:15–17; 2 Tim. 1:12; 4:7, 8). But he wrote it in the spirit of deep humility and commendable distrust in self. The words also imply earnest striving.’ (Hendriksen)

‘What is this language “somehow, to attain?” That is the language of humility and of hope. Paul knew he had not yet attained the resurrection, for he had not yet died. His physical resurrection was still a future hope. It is not that he is unsure of it, for Christ is already risen so the eventual resurrection is sure. The point he is making is that he is not there yet. He is still “pressing on.”‘(HSB)