It depends why you are finding it difficult, I'm assuming it's not a time issue because there really isn't any excuse to not find 30 minutes.

You have to find a way that works for you but I'll share my experience and hope it helps
I find that if I think about exercising I will often start trying to find reasons not to do it or just plain dwell on how tired I am, how much else I have to do or how unpleasant the exercise will be or how I'm not doing enough anyway. If I let myself go down that path I will end up missing the exercise that day and then the next day I'll convince myself it's not worth doing because I missed the previous day so obviously I'm not on target, The day after I decide I've blown that week so...................it's crazy I can write this down and yet still do this.

For me I've tried to remove as many obstacles as I can. The equipment I need is always to hand not put away in a cupboard. I exercise around my working and home commitments which vary daily but are generally pretty stable week to week. If I know my week is going to change I decide ahead of time when I'll do the exercise. My family and friend keep out the way at those times because they support me, even if they think I'm a bit obsessive about getting the exercise in. On the days when I don't go to work I put my workout clothes on when I get up, when I'm at work I go straight upstairs and changed when I get in. This has all become pretty much a routine and I do it mostly on autopilot but I did have to force myself for a couple of weeks. I refuse to let myself think about the exercise so I can't talk myself out of it. Once I've got started on the workout, if I'm finding it hard and I want to give up I concentrate on the reasons I'm doing it and tell myself it will be over soon because it's only 30 minutes.

I don't make exercising optional anymore. These are the things most people do everyday to survive/live- work, eat, sleep, clean, care, I added exercise to the list because it belongs there x