Youssef has seen very little first team action since his arrival from France as a teenager - just two appearances, in fact - but he is keen to show that he has grown up as a player and a person.
"Fitness was a problem when I first came here and was always injured but now I have a good fitness level," he says.
That was in evidence when he won Thursday's 'bleep' test - running at a pace set for you until there is only one man left standing!
Youssef was that man and he smiles:
"I was very tired after 14 or 15 minutes' solid running; I am working for myself to get a good fitness level and we will see what happens."
Youssef had a brief spell at Dutch club RBC Roosendaal this season, but he returned to England and says:
"I didn't really like the club so I am back here and trying to get in the team; I came here when I was 17 and it is my ambition to get in the first team.
"Obviously it is the manager's choice but I need games; if I get the chance hopefully I will take it this time.
"We had a chat at the start of the season and he said it was a fresh start for me; I have been working hard and I am just waiting for my time."
A spell elsewhere, on a temporary basis, is still on the cards though and Youssef says:
"I know the boss wants to put me out on loan; it could be a good thing if I can get maybe a second division club and play every week it would be good for me - and good for the future.
"Sometimes it is good to take one step back and two forward; if I score some goals at another club it would be important.
"I want to play for West Ham so I am going to wait for my chance; it won't be like last season when my head goes down - I will be stronger.
"I am just going to work hard to get in this team and maybe it is a good thing that I had these problems when I was young rather than 25 or 26 - I am still young and I feel more mature."
Youssef did have a loan spell back in France last season and he says:
"Last season I played eight games for Lille in the top league and got injured so it is frustrating being here in the first division and not playing - but that is football, and I have got to stay strong."
Youssef, whose partner is expecting a baby in February, now speaks good English and he adds:
"That helps a lot; when I first came there were six French players and I couldn't get involved with the other team mates but it is different now.
"We are all going out together for dinner after the football so it like a different life for me being in England.
"I am enjoying it now whereas I wasn't in the beginning - it is good."