It's pretty normal. Figure out first what you want from each side project. If your goal is to learn or play around with new "X" then it's fine to half-ass it, build the fun parts and then never look at it again. If you want to try and build a business and make money on the side then this is usually the time to not try out new "X" and instead stick to boring tech you know well.

Edit: for practical tips on keeping some momentum, just start with a tiny amount each day, like just 30-40 minutes after work or before. The next week you can add a little more ect.