You need to define what you think a productive day is and work back from there.
You reference that ur friends are all being really productive, what is it that they fill their day with which you would like to.
For me I don’t set myself x amount of hours from time a to time b because I am not motivated by the rigidity of it.
instead I have tasks or quotas for each subject that I try to fulfil (usually I fail but hey, setting the bar high works for me - it worked for Stalin)
What would you consider a productive day?