have you tried the 30 day challenge thingie? supposedly it creates a new habit for you
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so you want to have x in your life now. (x=whatever routine you picked)
besides the 30 day challenge, I'd also recommend you do x every day at the same time. supposedly this makes it easier for you to make it a habit. also, if you can do it in the same place too, that's supposed to also help reinforce it.
also, you can try creating an accountability system in your friends. assign checking up on you to a friend, if that's possible. they're supposed to call you up every day just before your time to do x and make sure you're gonna go through with it.
or alternatively, group up with friends. pick the most responsible person you know and try and work on x with them. sign up for singing classes with them, or agree to be their gym partner, or sign up for learning a new language with them (for memory training thingie).
if nothing else works, tell them that for every session of x you miss, you owe them 50$ (or whatever amount is appropriate for you). you go broke a couple of times and then voila you're suddenly responsible (cause being broke means being bored and hungry and that just sucks real bad)
. maybe put up a big board with a table on it where you have to write down your own attendance or lack there of.
you can set up a system of rewarding yourself for every session you attend, too.. even if it's just a pat on the back.
I hope any of this helps