Its all a load of rubbish!
In fact his words are stronger than that. The Greek word he uses is literally that which is thrown out, even excrement ... so we might even translate as "Its all a load of pooh!".
Well, what Paul actually writes is that it is all pooh in comparison with knowing Jesus. The things themselves are not actually rubbish, but he is saying that given the choice, he would choose knowing Jesus over any of these. Paul himself had a lot of certificates, he was the best of the best, but he now saw that knowing Jesus was more important than any of this. So don't junk your schoolwork, and do the best you can, but do it realising that ultimately knowing Jesus is a bigger deal.
When I went to university at the age of 18 I thought I knew about God - since I had been to church through my teens. Yet at uni I was confronted by the opportunity to actually know Jesus. This changed my life. Six months into my degree my tutor summoned me to his office. Once there he tried to convince me how successful I could be as an engineer, showing me previous pupils and how well they had done. As a fairly new Christian I only had limited Bible knowledge, but I had heard a talk on this Philippians passage. In the moment I said to my tutor "Maybe I can be a successful engineer, but compared to knowing Jesus its all a load of rubbish!".
Now let us be clear. There is nothing wrong or bad in the engineering itself. In fact I loved it, studied hard, and gained a good degree. Yet when it comes down to weighing this versus knowing Jesus, then Jesus wins every time. If it was ever to come to a crunch choice, my mind was already made up to choose Jesus.
This is because whenever we feel we are not good enough, not likeable, or that we don't qualify, I have discovered that Jesus has our bad stuff covered and can sort it. In Jesus God is saying to me a great big YES. Whenever we bury ourselves in our phones, ensuring we are in on the latest chat, we should know that at the very same time God is calling us to a much greater party, a much deeper and meaningful call that outstrips anything we could imagine ... and you are invited! The invitation is in knowing Jesus.
So I would summarise as whatever you want to do, whatever you are passionate about, then do it, and be the best you can at it. Yet do it whilst knowing Jesus, with Jesus as your greater priority. Everything we do here at church is not about getting some badge, but is in the hope that it helps people to know Jesus. There is no special 'church attendance' certificate ... but joining us in worship and at special events will hopefully be a good place to encounter Him.
Paul says 'I want to know Christ' - plain and simple. He goes on 'and know the power of his resurrection', because Jesus is alive and we can experience him by his Spirit today. That is what our baptism candidate has shared, talking of realising the Spirit's power in her life. Yet Paul also talks about 'participation in his sufferings, like him in his death'. That doesn't sound so positive! To be honest the way of Jesus is hard, it requires laying down your life that others might live. It means that things in us need to die - as symbolised by the person going down into the water.
We come back up in resurrection, to our new life knowing him. It is a journey ahead - Paul says 'I have not already obtained all this ... but press on'. We can go forward, pursuing the God given passions in us, that He will take with us to whole new levels. This is a journey of life laid down yet lived in resurrection power. It won't be comparing certificates, or even Facebook or Instagram 'Likes', but rather pursuing things of eternal significance such as changed lives, the bad made good.
So the bottom line is understand the comparison: what is good and what is ultimately of the utmost importance. Choose Jesus and make knowing Him your priority. Do whatever it takes to know Him and discover all He has in store for you.